I always just imagine if water was poured on the entire surface of the green, how would it run because of gravity. That being said, I suck at reading greens, I feel that a lot of the time I don't give myself a chance to sink a birdie putt because I mis-read it. Sometimes my best putting day is when I'm pushing or pulling putts, offsetting my mis-read
That first guy really made me laugh, his explanation was pretty fun and then he topped it off with running the putt by the hole outside of the camera's view.