Cannot play video because the resource is unavailable?

hi. So I moved my photos onto MyPassport as the storage on my Mac was full. After doing so I realised some videos were not playing. I’m not sure if this was caused by moving photos/videos on to the passport. The message that comes is “ Cannot play video as the resource is unavailable.” Any help as to why this is and/or what I can do to recover these videos?

the videos that don’t work do not appear on the passport. I have also tried edit with..QuickTime player which shows a message saying “an error occurred while preparing external edit. The operation couldn’t be completed.”

thank you