there are a few choices for movie playback on a series 60, one of the better ones is smartmovie form here..
http://www.lonelycatgames.com/index.php?note=smartmovie&chapter=smartmovie Download link is on the left of the page, uiq/symbian. Its the demo, which means you will have sections of you films in black and white. You will get an encoder to run on your pc and a player to install on your phone..........i have used this prog on quite a few phones and picture and sound quality is spot on.
Also, try this for movie encoding for free
http://divx.ppccool.com/ the films put thru this program will playback thru smartmovie too