Videos in email

Using my browser Firefox 73.0.1 and it is sandboxed.  I go to Yahoo mail and read a mail that has a video attached.  The video is usually an MP4.  With Sandboxie 5.33.1, the playback would fail due to not being able to find a codec.  Now with version 5.33.2 it fails with a message that the file could not be retrieved from a temp folder.  I have all the video applications in Firefox set to use my media player of choice.  If I use Firefox un-sandboxed, the videos play without issue.  What can I do about this.  hanks