IDK why you are running a t-stat for a 10 min test run anyway.
Also, the by-pass hose would let the coolant flow just fine even if the t-stat was in backwards. I suspect it either wasn't pumping properly or you didn't get all the air out of the system. I can't see the video, but if you weren't using coolant and the system had air in it or wasn't fully sealed...boil-over.