for a while I have been trying to do this effect but it never came out good.
@2008dare Your question has been moved to the Support thread sine it really wasn't a Feature Request. The only way I know to do this is to track the face as best as possible and apply that tracked data to a point that the image the image you wish to use is parented to. Place that image layer above the main layer and it should follow the track Hope that helps. There may be a good tutorial on YouTube though. I haven't searched for one yet.
Edit: This one might help. Same principal:
Ok thank I will check it ok I have been trying to do this for a long time thanks again!