Dog one is cool but i think its fake. k9 cops have special buzzers they wear that open the back door, then the dog comes out and goes nuts like you saw. This cop definitely didnt see the other guy coming nor did he feel like he had anything to fear from the original guy to buzz the door.
https://www.youtube.com/watch?v=2woeLKiz7rs
Not too mention it looks like the guy with the bat has one of those dog bite vests on.