diff --git a/pydantic_ai_slim/pydantic_ai/messages.py b/pydantic_ai_slim/pydantic_ai/messages.py
index 9019b81931..a5ab2aa741 100644
--- a/pydantic_ai_slim/pydantic_ai/messages.py
+++ b/pydantic_ai_slim/pydantic_ai/messages.py
@@ -2,14 +2,16 @@
 
 import base64
 import hashlib
+import mimetypes
 from abc import ABC, abstractmethod
 from collections.abc import Sequence
 from dataclasses import KW_ONLY, dataclass, field, replace
 from datetime import datetime
-from mimetypes import guess_type
+from mimetypes import MimeTypes
 from os import PathLike
 from pathlib import Path
 from typing import TYPE_CHECKING, Annotated, Any, Literal, TypeAlias, cast, overload
+from urllib.parse import urlparse
 
 import pydantic
 import pydantic_core
@@ -25,6 +27,27 @@
 if TYPE_CHECKING:
     from .models.instrumented import InstrumentationSettings
 
+_mime_types = MimeTypes(tuple(mimetypes.knownfiles))
+# Register manually MIME types that are not in the standard library or override standard ones
+# Document types
+_mime_types.add_type('text/markdown', '.mdx')
+_mime_types.add_type('text/x-asciidoc', '.asciidoc')
+
+# Video types
+_mime_types.add_type('video/3gpp', '.three_gp')
+_mime_types.add_type('video/x-flv', '.flv')
+_mime_types.add_type('video/x-matroska', '.mkv')
+_mime_types.add_type('video/x-ms-wmv', '.wmv')
+
+# Audio types
+_mime_types.add_type('audio/flac', '.flac')
+_mime_types.add_type('audio/mpeg', '.mp3')
+_mime_types.add_type('audio/ogg', '.oga')
+# override stdlib mimetypes that use x- prefix with standard types
+_mime_types.add_type('audio/aac', '.aac')
+_mime_types.add_type('audio/aiff', '.aiff')
+_mime_types.add_type('audio/wav', '.wav')
+
 
 AudioMediaType: TypeAlias = Literal['audio/wav', 'audio/mpeg', 'audio/ogg', 'audio/flac', 'audio/aiff', 'audio/aac']
 ImageMediaType: TypeAlias = Literal['image/jpeg', 'image/png', 'image/gif', 'image/webp']
@@ -226,38 +249,27 @@ def __init__(
         )
         self.kind = kind
 
-    def _infer_media_type(self) -> VideoMediaType:
+    def _infer_media_type(self) -> str:
         """Return the media type of the video, based on the url."""
-        if self.url.endswith('.mkv'):
-            return 'video/x-matroska'
-        elif self.url.endswith('.mov'):
-            return 'video/quicktime'
-        elif self.url.endswith('.mp4'):
-            return 'video/mp4'
-        elif self.url.endswith('.webm'):
-            return 'video/webm'
-        elif self.url.endswith('.flv'):
-            return 'video/x-flv'
-        elif self.url.endswith(('.mpeg', '.mpg')):
-            return 'video/mpeg'
-        elif self.url.endswith('.wmv'):
-            return 'video/x-ms-wmv'
-        elif self.url.endswith('.three_gp'):
-            return 'video/3gpp'
         # Assume that YouTube videos are mp4 because there would be no extension
         # to infer from. This should not be a problem, as Gemini disregards media
         # type for YouTube URLs.
-        elif self.is_youtube:
+        if self.is_youtube:
             return 'video/mp4'
-        else:
+
+        mime_type, _ = _mime_types.guess_type(self.url)
+        if mime_type is None:
             raise ValueError(
                 f'Could not infer media type from video URL: {self.url}. Explicitly provide a `media_type` instead.'
             )
+        return mime_type
 
     @property
     def is_youtube(self) -> bool:
         """True if the URL has a YouTube domain."""
-        return self.url.startswith(('https://youtu.be/', 'https://youtube.com/', 'https://www.youtube.com/'))
+        parsed = urlparse(self.url)
+        hostname = parsed.hostname or ''
+        return hostname in ('youtu.be', 'youtube.com', 'www.youtube.com')
 
     @property
     def format(self) -> VideoFormat:
@@ -302,28 +314,18 @@ def __init__(
         )
         self.kind = kind
 
-    def _infer_media_type(self) -> AudioMediaType:
+    def _infer_media_type(self) -> str:
         """Return the media type of the audio file, based on the url.
 
         References:
         - Gemini: https://ai.google.dev/gemini-api/docs/audio#supported-formats
         """
-        if self.url.endswith('.mp3'):
-            return 'audio/mpeg'
-        if self.url.endswith('.wav'):
-            return 'audio/wav'
-        if self.url.endswith('.flac'):
-            return 'audio/flac'
-        if self.url.endswith('.oga'):
-            return 'audio/ogg'
-        if self.url.endswith('.aiff'):
-            return 'audio/aiff'
-        if self.url.endswith('.aac'):
-            return 'audio/aac'
-
-        raise ValueError(
-            f'Could not infer media type from audio URL: {self.url}. Explicitly provide a `media_type` instead.'
-        )
+        mime_type, _ = _mime_types.guess_type(self.url)
+        if mime_type is None:
+            raise ValueError(
+                f'Could not infer media type from audio URL: {self.url}. Explicitly provide a `media_type` instead.'
+            )
+        return mime_type
 
     @property
     def format(self) -> AudioFormat:
@@ -365,20 +367,14 @@ def __init__(
         )
         self.kind = kind
 
-    def _infer_media_type(self) -> ImageMediaType:
+    def _infer_media_type(self) -> str:
         """Return the media type of the image, based on the url."""
-        if self.url.endswith(('.jpg', '.jpeg')):
-            return 'image/jpeg'
-        elif self.url.endswith('.png'):
-            return 'image/png'
-        elif self.url.endswith('.gif'):
-            return 'image/gif'
-        elif self.url.endswith('.webp'):
-            return 'image/webp'
-        else:
+        mime_type, _ = _mime_types.guess_type(self.url)
+        if mime_type is None:
             raise ValueError(
                 f'Could not infer media type from image URL: {self.url}. Explicitly provide a `media_type` instead.'
             )
+        return mime_type
 
     @property
     def format(self) -> ImageFormat:
@@ -425,33 +421,12 @@ def __init__(
 
     def _infer_media_type(self) -> str:
         """Return the media type of the document, based on the url."""
-        # Common document types are hardcoded here as mime-type support for these
-        # extensions varies across operating systems.
-        if self.url.endswith(('.md', '.mdx', '.markdown')):
-            return 'text/markdown'
-        elif self.url.endswith('.asciidoc'):
-            return 'text/x-asciidoc'
-        elif self.url.endswith('.txt'):
-            return 'text/plain'
-        elif self.url.endswith('.pdf'):
-            return 'application/pdf'
-        elif self.url.endswith('.rtf'):
-            return 'application/rtf'
-        elif self.url.endswith('.doc'):
-            return 'application/msword'
-        elif self.url.endswith('.docx'):
-            return 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
-        elif self.url.endswith('.xls'):
-            return 'application/vnd.ms-excel'
-        elif self.url.endswith('.xlsx'):
-            return 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
-
-        type_, _ = guess_type(self.url)
-        if type_ is None:
+        mime_type, _ = _mime_types.guess_type(self.url)
+        if mime_type is None:
             raise ValueError(
                 f'Could not infer media type from document URL: {self.url}. Explicitly provide a `media_type` instead.'
             )
-        return type_
+        return mime_type
 
     @property
     def format(self) -> DocumentFormat:
@@ -545,7 +520,7 @@ def from_path(cls, path: PathLike[str]) -> BinaryContent:
         path = Path(path)
         if not path.exists():
             raise FileNotFoundError(f'File not found: {path}')
-        media_type, _ = guess_type(path)
+        media_type, _ = _mime_types.guess_type(path)
         if media_type is None:
             media_type = 'application/octet-stream'
 
diff --git a/tests/test_messages.py b/tests/test_messages.py
index 943d68fe8c..488d847b62 100644
--- a/tests/test_messages.py
+++ b/tests/test_messages.py
@@ -333,6 +333,78 @@ def test_video_url_invalid():
         VideoUrl('foobar.potato').media_type
 
 
+@pytest.mark.parametrize(
+    'url,media_type,format',
+    [
+        pytest.param(
+            'https://example.com/video.mp4?query=param',
+            'video/mp4',
+            'mp4',
+            id='mp4_with_query',
+        ),
+        pytest.param(
+            'https://example.com/video.webm?X-Amz-Algorithm=AWS4-HMAC-SHA256',
+            'video/webm',
+            'webm',
+            id='webm_with_aws_params',
+        ),
+    ],
+)
+def test_video_url_with_query_parameters(url: str, media_type: str, format: str):
+    """Test that VideoUrl correctly infers media type from URLs with query parameters (e.g., presigned URLs)."""
+    video_url = VideoUrl(url)
+    assert video_url.media_type == media_type
+    assert video_url.format == format
+
+
+@pytest.mark.parametrize(
+    'url,media_type,format',
+    [
+        pytest.param(
+            'https://example.com/audio.mp3?query=param',
+            'audio/mpeg',
+            'mp3',
+            id='mp3_with_query',
+        ),
+        pytest.param(
+            'https://example.com/audio.wav?X-Amz-Algorithm=AWS4-HMAC-SHA256',
+            'audio/wav',
+            'wav',
+            id='wav_with_aws_params',
+        ),
+    ],
+)
+def test_audio_url_with_query_parameters(url: str, media_type: str, format: str):
+    """Test that AudioUrl correctly infers media type from URLs with query parameters (e.g., presigned URLs)."""
+    audio_url = AudioUrl(url)
+    assert audio_url.media_type == media_type
+    assert audio_url.format == format
+
+
+@pytest.mark.parametrize(
+    'url,media_type,format',
+    [
+        pytest.param(
+            'https://example.com/image.png?query=param',
+            'image/png',
+            'png',
+            id='png_with_query',
+        ),
+        pytest.param(
+            'https://example.com/image.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256',
+            'image/jpeg',
+            'jpeg',
+            id='jpg_with_aws_params',
+        ),
+    ],
+)
+def test_image_url_with_query_parameters(url: str, media_type: str, format: str):
+    """Test that ImageUrl correctly infers media type from URLs with query parameters (e.g., presigned URLs)."""
+    image_url = ImageUrl(url)
+    assert image_url.media_type == media_type
+    assert image_url.format == format
+
+
 def test_thinking_part_delta_apply_to_thinking_part_delta():
     """Test lines 768-775: Apply ThinkingPartDelta to another ThinkingPartDelta."""
     original_delta = ThinkingPartDelta(