Also had some griefs with the gameplay shortly afterwhat the heck is triggering the defeat of the goat-yeti, and why the heck do I have to figure this out by trial-and-dying. I still dont have a clue what does it, I think you need to get up close to get the quicktime events twice?
The answer to your question I think
is that you have to get enough hits on it to trigger the event. Similarly to the boss-guy on the train, it's not just time dependant. A good way of fighting the 'goat-yeti' is to keep running (or circling him as close as possible so that he can't catch you) and keep (blind) firing. He'll catch you eventually, but as long as your health is good, he won't kill you. Repeat this until you beat him