Here is a slightly modified version of a short documentary I did a few years ago about my experience with two snow leopards attacking a dzo (part cow - part yak). At the time, it was the only footage of them attacking another animal, and still the only proof of (other than anecdotal evidence) leopards hunting animals much larger than them.
Admittedly, I posted this a few years ago, but Youtube made me take it down due to two images. I got permission in 2004, but couldn't contact National Geographic again about written permission. A few pictures were altered, and a little color correction was done in this version. Enjoy.