I saw the original video a day or two ago. It is video of a row of security monitors, NOT the direct feed from the security cameras.
As to why he started recording before the kiss, I'm going to guess that there was some activity earlier that caused him to think that he might get something juicy if he recorded those monitors.
It may be that there’s some x-rated stuff on the tape but the person decided he didn’t want to show that to the world....YET!
The congressman jumped up immediately and admitted guilt. That tells me there’s more coming.