You could tell us the type cell phone.
It’s been my experience that unless you buy the cell phone manufacturers software, it will be really painful to get features like video to actually work.
Try playing it using iTunes
I am guessing it is in .3gp format and if that is the case I have found that nokia’s player works better than most codecs and other players.
http://nokia-multimedia-player.en.softonic.com/symbian