I'm planning to save the video of them in the bedroom for blackmail later.
Why would you blackmail someone? What are you going to do when they find out?
I am wondering what he does with this kind of stuff.
Blackmailing people is a crime. You should not do it because you could be the one that winds up in jail.
He shouldn't have done all these if he doesn't want to be black mail. If I can get him in jail, that is all I want to achieve.
If someone has done something illegal than you should turn over the evidence immediately to the proper authorities. By holding onto the evidence and blackmailing them you are showing that you don't care about justice, but rather your own goals and needs. This kind of behavior enables the perpetrator to continue to be free and act in their deceitful manner.