If the software doesn't have some sort of Recovery features, then the videos are long gone especially if they've been modified. I recommend transferring the video files to the PC and then use a media player to view them. For this procedure, VLC should be used as it supports reading broken files.
If VLC won't play them, then it's impossible to recover them. For future, I recommend avoiding this type of applications. If you have anything to protect, upload them to a cloud storage service, activate 2nd step authentication and everything should be kept secure.