*HELP*:how to get video onto camera!

[Gamertag07]

ok. Im completely new to the world of cameras and this forum looked like the place to turn to for help. Ive just recently purchaced a SONYCybershot DSC-W50 and im loving it so far. But i recently needed to place a photo from my computer onto my camera so i could show a friend at shcool. That was easy enough i just renamed the file DSC0**** and placed it in the ***MSDCF file. GREAT! but then i thought the procecess for putting a movie(mpg.) file onto the camera would be basically the same. So i renamed a video from my computer MOV***** and placed it in the same file. NOTHING...frustrated i wondered if i needed the THM. file for it to work, but upon deleting the THM. file for another movie, that movie still played?...then i deleted a movie that i had already taken off my camera and i had stored it on my computer. I then tried placing the video that i had taken off my camera and stored on my computer back on my camera and WALL-LA! it worked with/without the THM. file .....so HOW DO I GET A VIDEO THAT WASNT ORIGINALLY TAKEN BY MY CAMERA AND PLACE IT ON MY CAMERA SO THAT IT WORKS?
Thank you for your time,
Gamertag07:cool: