Greyhounds, as a breed don't/can't jump so a 4' fence is perfect for them. Galgos (Spanish Greyhounds) are fantastic jumpers. There's a video of a Galgo jumping onto a low roof.
Well, that's even more proof that he's happy with you! Seems like you can just tell by the look on his face when he came up to you after he was finished running- seems like he was smiling at you!
I didn't mind your voice at all, and I think he liked you cheering him on!!
Ima- that was my first thought too :P Mason is like, whatever dude.
Him running kind of reminds me of the old cartoons where their legs are moving so fast in so many directions, that all four legs go out side and they collapse on their belly- had me laughing for sure!