Fix for displaying videos on AutoGen Studio

[brotsky]

Why are these changes needed?

This fixes a problem I noticed when generating MP4 videos. The video's file type is unknown in its metadata so I used the file extension instead.

Related issue number

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[brotsky]

This was the problem:

And this is with my solution:

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2ca8aae) 30.41% compared to head (e963b2a) 30.41%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1084   +/-   ##
=======================================
  Coverage   30.41%   30.41%           
=======================================
  Files          32       32           
  Lines        4301     4301           
  Branches      993      993           
=======================================
  Hits         1308     1308           
  Misses       2899     2899           
  Partials       94       94           

Flag	Coverage Δ
unittests	30.36% <ø> (ø)

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[gitguardian]

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[rysweet]

This PR is against AutoGen 0.2. AutoGen 0.2 has been moved to the 0.2 branch. Please rebase your PR on the 0.2 branch or update it to work with the new AutoGen 0.4 that is now in main.

[victordibia]

Closing this as stale for now.

[rysweet]

actually closing it