Please forgive me If this isn't the right place for my question, but after searching around a bit i find that I do not know what to search for! I can't think of what this effect would be called and have been trying to figure it out for about 2 weeks. All I want to do is create an effect wherein I replace the heads in a video with still images from pictures I have. This little flash video is pretty much what Im trying to figure out.

ZOMG ZUFALL! #1494

Im looking for someone to point me in the right direction, with maybe what to search for to find a tutorial or even directions. I know this is cheesy but I'm working on a video and need this for a joke. I do plan on using Sony Vegas if possible.

Not really a tutorial, more of a detailed collection of pointers....

Simple version (one photo):
Edit your photo in your favourite package and make everything EXCEPT the bit your want to keep (ie the face) the same colour - make sure that colour doesn't appear in the face itself (green is common).
Put your background video on track 2
Put your still on track 1
Drop a Sony Chroma Keyer effect onto your still on track 1 and select the background colour as the colour to key out (click on the dropper tool then click on background area of the still).
Now the background video should show through, leaving just the face superimposed.
That's the easy bit!
The tricky (or rather time consuming bit) is using track motion on track 1 to move the face around in sync with the background video.

Just add more tracks (making sure they're above the background track) for more faces.

If your photo editing suite allows you to export targa or png files with transparency, you could use transparent for the background of the still rather than a colour and won't need the chromakey effect.

__________________
Tim

Thanks a lot! I'm going to put this to use and see if I can get what I'm looking for. Any Idea what this process/technique is called so I can search it for further reading? What about using this process with video of a face rather than a photograph?

Try searching chromakey, overlay, superimpose. I've probbably missed an obvious one though

Exactly the same principle, but rather than cropping the face within a photo editor, you'd need to get to grips with the bezier masks within Vegas' pan & crop.

__________________
Tim