i was mostly interested about lived-through experiences of people who also host videos. for example i encountered a case where audio file had a video track in it. it baffled me until i found it was the album cover/image as motion-jpeg. so i had to adjust the input validation. or that my own generated mp3 audio file from a video file was not passing a 90% ffprobe reliability threshold so again i had to alter validation... and things like that. like people mentioned that yuv420 profile being important. i also heard about malicious code being in video files or containers in general which can cause some issues. though i do not know much about it.