This brotherly throwdown is the work of Jordan Tseng, 17, who writes in the video's YouTube introduction, "I'm going to have the University entrance examination [in] 2 weeks." Yeah. Just go ahead and pass him already.
That's assuming Tseng, of Taiwan, is going to study film and/or animation, of course, because this very well done LEGO stop-motion battle involving Thor and Loki (and Loki in a mech) is several cuts above that of a hobbyist. People will rightly rave about the visuals and the post-production work, but I think the sound engineering is also very well done, and glues the whole thing together.
On his blog, Jordan says he's been making films like this since he was 14. Over the summer he put together this, a fight between an Iron Man action figure and a Transformer. At 1:55, it required about 1,700 images, so you can expect this one, at 2:30, needed even more painstaking work.
Lego Thor Stop motion: Brother's fight [YouTube, h/t Ken Y.]