This has happened a number of times now. After shooting some video on my iPhone, then transferring it to my iPad, I attempted to transfer it from my iPad to the SD card on my Media Drive. The transfer looked successful according to the Media Drive, but the video would not play in the Media Drive app or on my computer.
It happened again just now, so I made a second attempt to transfer; same thing. Then, on the third attempt, the video played via the Media Drive app and on the computer.
I would hate to think of losing precious video (ok, they’re not all precious, but once in a while…) thinking they’re safely backed up on my Media Drive when they’re not. At least it appears I can verify that the transfer worked (by playing the transferred video) before I delete the original.