I dunno, just watched it and it seems like they built in some tracking along with a compositing program. All that they did show off wasn't very difficult at all to do, the only thing that would require a bit of effort is the flower shop bit.
I'm not a compositor, don't care for it much myself but I seen this stuff being done quite a bit and I've done some of it myself through my ghetto techniques lol.
If they actually showed how they did it, like in the program maybe it would be a lot easier, I dunno, but overall seems rather average.