Never, ever, EVER forget how much of a difference your editor can make. Also, don't ever underestimate the power of laugh tracks.
This mashup, Game of Thrones as Seinfeld, just about made me fall out of my chair. I'm a big fan of The Song of Ice and Fire, more of the books than the show, but the show is pretty beautiful, and I've watched plenty of Seinfeld, and I love what these people are doing. They overlaid laugh track on the video and did some simple cuts, but I'm pretty certain that the two main scenes in each episode here are powered dominantly by the Seinfeld-esque rolling laugh track.
Anyway, give the first two episodes a looksee. I'd imagine that it's probably slightly less funny if you haven't seen both shows, but hey, that's life.
Check it out.