I feel like I know the basic rules of competition judo, but some things I see in videos make me question why the refs make certain calls. For instance when the fight goes to the ground, I don't see why they let it continue sometimes and stop it bringing the competitors back to their feet others. I was also watching the Olympic bronze Rousy vs Boem fight and still don't understand the mechanism behind which Rousy won. The final exchange looked to my novice eyes like an awkward Harai Goshi attempt that sent them tumbling over each other, not what looked to me like an Ippon or anything.