Can use the media transfer software that comes with it or transfer them manually. The software will flag some things as unplayable that WILL work however and try to convert them.
I recommend converting them ahead of time and transferring manually to the Video directory. DivX and Xvid work well and convert quicker than most video formats. Videos HAVE to be 320x240 or smaller. It will scale up but not down.
I use the free
Super converter.