I have jailbroken iPad 2, so I'm curious where OplayerHD app stores movies? It's not under it's Documents folder, and you can't view them in iTunes App share space. At least not for long. It seems after you copy a movie, upon launching OplayerHD hides it somewhere removing from it's Documents folder.
EDIT: Sorry I found answer myself. It's under .OplayerDonotBackupAVFiles folder.