Is anything like this possible in Blender? If so, can someone tell me how?
Sure, but you need to learn motion tracking and camera mapping, and a few things in between. Lots of tutorials exist on those topics that can be applied directly to blender toolset. There’s also a couple specifically for blender and some great docs on the wiki… but I’m gonna make you use the search function 
… now it’s back to work for me…
Ok, because I know that Colin Levy used it in his commercial. Was blender the only software he used to replace the background?
http://nz.youtube.com/watch?v=seuCf3lbBn4 Wouldn’t this eliminate the need for motion tracking? Or would motion tracking with an external program just make the job easier? I really didn’t know that this was possible in blender. I really won’t need any other fx programs if blender can create effects like this.
Wow, that looked complicated. Persoanlly I thik it would just be easier to throw it into a tracker (VooDoo or Icarus or some such). And let it do it’s thing and then just use it in Blender. That tut looked way to complicated and I don’t even want to thikn about doing it for anything more complicated than that.
But then thats just me.