this seems quite likely. But is there no way to recover the files?
You can always try copying them from the current problem drive to your system and hope that copied files are playable. It will all depend on the specific nature of the original problem. For instance, if the main problem is caused by an inability of the flashdrive to read and transfer the data fast enough for the players to play the video properly but the data can still be read correctly (albeit too slow for playback), then the file copy "handshaking" and error correction routines may still allow you make a "clean" copy of the files. On the other hand, if the main problem is that the flashdrive files are already corrupted or simply can't be read correctly, then it is doubtful you can "recover" them.