IMHO, I would suck it up and let your son go to the wedding. He will love you for it and remember that you put him first. Weddings are a big deal, and I'm sure it's important to him that he's there. Who cares what your ex thinks, or does. Do the right thing for you kid.
With the other situations (sleep over's, her daughters b-day, etc.). We have had the same issues. My husband's kids know their schedule, and my husband told them that if they want to do a sleep over, go to a b-day party, etc during his weekends they need to discuss it with him (since he's the parent in charge at that time) or they don't go. If their mom schedules something during my husband's parenting time (family visit, for example) and they're upset that they can't be there - my husband simply tells them "Honey, your mom knows when you're with her and when you're with me. She should schedule it during her time." This is not to say that he won't work with her if she's willing to trade weekends, but he doesn't let her put the blame on him if she wants to have her cake and eat it too.
I watched the video. She's being a pain, but don't let it get to you. I wouldn't pay any bills without a copy of the receipt, number one. Send her an e-mail requesting a copy of the receipts, then mail her a check referencing the receipt number and name of the company in the memo field. Just like any other bill. If you think she'll pretend she didn't get it send it to her certified mail with return receipt. If she won't sign for it that's on her.
I think you might be at risk for some legal trouble with the video, since you don't have her permission. I would resist the temptation to do stuff like that. You can keep it for yourself if you feel the need, but I wouldn't post it online. Especially since she asks you not to record her in the video.