can not open some of videos in photoshop cc 2014

hi.i am really confused which videos can open and which videos can't open in photoshop.i open some of long videos easily but some shorter videos show message:could not compelete your request because the video file could not be opened.i downloaded my videos with any quality from youtube.i searched a lot every where but i couldn't fix it (restartin,holding alt+shift+ctrl & ...).this is so intresting some videos with same properties opened easily.how can i fix it?please help me i need it too much 😞