this question has been asked over and over and over and over. and again, no. its not gonna happen without you buying extra video recording hardware. while it is entirely possible to do from a software standpoint, there is not enough processor power to both play a game and dump 30 frames a second to the SD card or USB drive or whatever - let alone, capture the frames and convert them into an avi or any sort of video that you would be able to play a video player.
stop being cheap, go cut 5 or 6 lawns, and buy a video recording dongle for your computer