Good video! Big browns will eat their smaller relatives and cousins. I was helping stock browns on the Hiwassee several years ago. The guide I was with (furnishing the raft and oar-time) saw a large brown break the surface, chasing one of the stockers we had just put into the river.
FWIW, I recall reading in Sports Afield (when it was printed on animal hides and papyrus) about guys who would fish at night (where permitted) with big deer hair mouse patterns and catch huge browns.