This issue has been brought up a couple of times.
The video-recorded file in FS is just a file containing directions to the simulator.
It's not a viewable video itself, so you need the simulator to watch it.
However, with the use of motion-capturing programs such as FRAPS you can record a movie in AVI format.
FRAPS saves every frame as a bmp. file so you MUST compress the movie afterwards.
Seach the forum, I bet you'll find tons of stuff here.
If you want to see how the result can be, here's a movie I made, featuring an Airbus A330 landing.
http://webb.informatik.gu.se/~s02henke/nexus/thomascooka3302.avi