diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index b215c56408503a..e90d6e6759db1f 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -1045,7 +1045,7 @@ mimetypes
   (Contributed by Benedikt Johannes, Charlie Lin, Foolbar, Gil Forcada and
   John Franey
   in :gh:`144217`, :gh:`145720`, :gh:`140937`, :gh:`139959`, :gh:`145698`,
-  :gh:`145718`, :gh:`145918`, and :gh:`144213`.)
+  :gh:`145718`, :gh:`146342`, :gh:`145918`, and :gh:`144213`.)
 * Rename ``application/x-texinfo`` to ``application/texinfo``.
   (Contributed by Charlie Lin in :gh:`140165`.)
 * Changed the MIME type for ``.ai`` files to ``application/pdf``.
diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index ad18db09f6b340..3f4d39978f1b93 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -672,8 +672,13 @@ def _default_mime_types():
         '.sgml'   : 'text/x-sgml',
         '.vcf'    : 'text/x-vcard',
         '.xml'    : 'text/xml',
+        '.3gp'    : 'video/3gpp',
+        '.3g2'    : 'video/3gpp2',
+        '.m4s'    : 'video/iso.segment',
+        '.lot'    : 'video/lottie+json',
         '.mkv'    : 'video/matroska',
         '.mk3d'   : 'video/matroska-3d',
+        '.mj2'    : 'video/mj2',
         '.mp4'    : 'video/mp4',
         '.mpeg'   : 'video/mpeg',
         '.m1v'    : 'video/mpeg',
@@ -683,6 +688,12 @@ def _default_mime_types():
         '.ogv'    : 'video/ogg',
         '.mov'    : 'video/quicktime',
         '.qt'     : 'video/quicktime',
+        '.pyv'    : 'video/vnd.ms-playready.media.pyv',
+        '.blk'    : 'video/vnd.radgamettools.bink',
+        '.bk2'    : 'video/vnd.radgamettools.bink',
+        '.sswf'   : 'video/vnd.sealed.swf',
+        '.ssw'    : 'video/vnd.sealed.swf',
+        '.yt'     : 'video/vnd.youtube.yt',
         '.webm'   : 'video/webm',
         '.avi'    : 'video/vnd.avi',
         '.m4v'    : 'video/x-m4v',
diff --git a/Misc/NEWS.d/next/Library/2026-03-23-20-14-57.gh-issue-146341.JSTJlL.rst b/Misc/NEWS.d/next/Library/2026-03-23-20-14-57.gh-issue-146341.JSTJlL.rst
new file mode 100644
index 00000000000000..db3ee129490848
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-03-23-20-14-57.gh-issue-146341.JSTJlL.rst
@@ -0,0 +1,13 @@
+Add the following MIME types corresponding to file extensions:
+
+``.3gp``   for ``video/3gpp``
+``.3g2``   for ``video/3gpp2``
+``.m4s``   for ``video/iso.segment``
+``.lot``   for ``video/lottie+json``
+``.mj2``   for ``video/mj2``
+``.pyv``   for ``video/vnd.ms-playready.media.pyv``
+``.blk`` and ``.bk2`` for ``video/vnd.radgamettools.bink``
+``.sswf`` and ``.ssw`` for ``video/vnd.sealed.swf``
+``.yt``    for ``video/vnd.youtube.yt``
+
+(Contributed by Charlie Lin in :gh:`146342`.)