Ok so messing around, I shot a short of my hand "firing" a gun in front of a green screen. Then I added in a muzzle flash with the chroma key settings. It worked great, however the area behind my hand is black. I'm trying to figure out if I can put a background image in between the gun footage and the muzzle flash. I tried adding another video track and put the background in but... it covered up the muzzle flash. Any thoughts.

Thanks