I purchased Recuva professional to recover several hundred movie files I accidentally deleted via a script.
After running, it found about half of them. Of those, about 2/3rds were marked as "excellent".
After restoring them however, the files all appear to be broken. They will play with VLC for a minute or so, then the video and audio drop out. Scanning with ffmpeg reports errors. So, I'm wondering, how would the recovery process break all these files? Because they're all unusable now.
I have had this issue as well. Just a hunch as I'm not pro but I have attributed the issue in my case to file compression....zip files. I've noticed that some of the videos I had stored on a backup drive were kept in zip files. It's as if Recuva thinks its recovering mp4s when it's actually picking up the zipped version of the file. I finally gave up and deleted the corrupted recovers because I wasn't comfortable shelling out money for video specific repair software to find them utterly useless.
Fragmentation can play a part in hampering the recovery process.