Unconvinced. LTT has 1 or 2 good videos for every 30 videos they release. Maybe the face helps people click the bad videos, but the good videos stand for themselves and it's likely that he would be successful without playing the game. (His all time most popular video doesn't have a thumbnail of him making a weird face. It's his most popular video of all time because his guest was exceedingly entertaining.)
(Also, I don't mean for this to be an anti-Linus post. How he built LMG is a great story and he deserves the success he's achieved.)
Very offtopic but, at first I thought you said L1T and we almost had to take this outside. Level1Techs is awesome. Can't say much for LinusTechTips as it's targeting a different audience, though the young man does seem charismatic.
(Also, I don't mean for this to be an anti-Linus post. How he built LMG is a great story and he deserves the success he's achieved.)