Cheap cards cannot keep up with the write speed of HD video, leading to the "49 vids" buffer crash.
Do you have the of the videos that aren't playing, or is the SD card not being recognized at all? hiddenzone spy cam 17861834 49 vids fix
A more user-friendly (though often paid) option that can specifically target "hidden" partitions often created by spy cams. 4. Prevent Future Crashes Cheap cards cannot keep up with the write
Troubleshooting the HiddenZone Spy Cam: How to Fix Video Playback Issues hiddenzone spy cam 17861834 49 vids fix
This is a free, powerful open-source tool that ignores the file system and looks for the raw data signatures of video files.