That was pretty good. It certainly can be exciting.

When the bigger second one showed up, I thought that might have been what spooked the first one, as in possibly the moose that broke the right antler off the first one. Then, at same spot, the second caught the bloke's scent so that was it, likely.
They do like to circle the caller to get the scent. They are expecting to smell the other bull and a horny cow- the long wavering call.