A great "all-rounder." It has a dedicated "Video Recovery" feature that can reassemble fragmented video files, which is common in DVR overwriting cycles. PhotoRec (Free/Open Source):
Despite the name, it is a powerhouse for video recovery. It supports deep scanning for various DVR file systems and can repair corrupt video files (MP4, MOV, AVI) during the process. Dolphin DVR Pro: Dvr Recovery Software With Crack
If you have deleted footage or a corrupted hard drive, these professional tools offer free trials to see if your data is actually recoverable before you pay: Stellar Photo Recovery: A great "all-rounder