Might want to explain a bit more.
take a real walkthrough video and merge it with a virtual tour.
I have a video of a site (architectural) and want to superimpose a 3d model walkthrough done in revit and merge them together.
Only thing I can think of is adjusting size, position, of virtual tour to 'match' (as close as possible) portions of your walkthrough, and use opacity to go back and forth between them. Hopefully the size change would be DOWN (less than 100%) and not UP.
In movies a combination of live action and 3d stuff is done with green screens etc., so that's not gonna happen unless you somehow mask figures with some secret super duper magic and ADD green screen ?