[ Music & Music Players ] Open Question : ipod nano video problems?

hi am have some problems with my new 4th gen ipod i got it from a friend and well it worked fine but know it is have some sorta video problem. the music to the videos fine its just that instead of a video i get slow modhion images every 3 sec it gose to anouther fram way ahead i know it can play them normaly cus i hade been playing them for at least a week with out this problem