Any way you can record what you're doing on your computer, by computer? Like a replay?

Depends on what you are trying to record. There are programs like jing and camstudio which will record video segments of what you see on your screen, although not the whole screen. this is very common for youtube videos. There are also keylogger programs which record everything typed on your keyboard, logins and passwords included. Some video cards also have an RCA plug or s-video connection for video output, which can be connected to camcorders, vcr's (they still have those, right?) or dvd-burners. Pretty wide-open question, so hope that helps.