Call for review: video audio fix

Hello Everyone,

This pull request fixes an issue we had with the audio from some videos not playing correctly. We determined the best solution was to remove the problematic mp4 files and leave only the webm files which are now more widely supported than when the rule was originally written.

If you have any concerns with the change, please leave a review within the next week: https://github.com/act-rules/act-rules.github.io/pull/1662

Regards,
Trevor Bostic

Trevor Bostic
Senior Software Engineer
E-Mail: tbostic@mitre.org
Phone: 703-983-9916
The MITRE Corporation