That's a Marine CH-46 ( a Sea Knight, not a Chinook) from 4-5 years ago. It was doing a VBSS (visit, board, search and seizure) exercise for an upcoming deployment off the San Diego coast. He came in too fast, too low, and didn't have enough power to prevent from settling while decelerating. I'm not sure on this mission, but usually the intent is not to land on the boat. Usually the Marines would fastrope out of the helicopter onto the deck. However,this time, settling into the deck, he tries to take off again, but one of the main mounts got caught in the man overboard netting, causing a rolling moment. I can't remember how many died, but luckily the boats behind were full of SEALs or divers and they were able to rescue several onboard.
Bill