I mean, he always smiles after as if it wasn't serious that at all after, always. and jokes to his friends after trashing them (seems like he cares, after all). you can hear it in his voice, if you were a native speaker.
about the act, it's interesting to viewers I guess, rather than watching some stone face with no personality pros who aren't that big to watch them for their skill. (talking about all t2 pros, it's just boring to watch) maybe that's why they have only 100 viewers watching, deko always has couple thousands, for instance. (but he is nowhere near popular in eng-speaking community) and he is not that big on youtube, as well.