Combining Clips; Black ops: Theater Mode?

I uploaded a video from Cracked which had 4 small clips of me sniping, kinda like a minitage. altogether it last 19 seconds. then i uploaded and rendered it to callofduty.com , so then i playbacked another video which only had 2 small clips of me sniping. this was on crisis. now is there anyway to combine the video of cracked and crisis together? so i cood have 6 clips in the video? Im planning to make more videos on diff. maps and combine them. is there anyway to do that?