You mean changing the .flv video or file?
If its a video, and its a .flv , simply:
1) Right click it
2) Press open
3) Tick the second button
4) Find your window media player
5) once it is open and you are watching it, go to FILE
6) sAVE AS
7) nameyoulike.avi <--- or for PSP or iPod Video, its namehere.mp4

but catapult idea is probably better, this is only if the above does not work.

=)