8e2915d70b
This reverts commit 7360db05b43741c2dfa1fd024e9c2f013ed97c9e. This commit was added as an attempt to fix #6046. Unfortunately, the fix is completely wrong. As reported on #10359, embedded thumbnails are not displayed in VLC, and Se7en on IRC reports that the embedded thumbnail misleads mpv as well. The correct way is using -attachment of ffmpeg, while the current run_ffmpeg_multiple_files API can't handle it cleanly.