I'm going to offer an alterative, perhaps controversial theory: Mark is an abused partner.
His demeanour. The look on his face. His posture. His presence. He's very unhappy. Depressed. Sad. He doesn't appear content or relaxed at all.
I think Charlotte is an abusive partner, more so when she's had a drink. I believe she's controlling Mark, the kids, the household. I believe everyone has to march to the beat of her drum. The notes from the kids are written to appease her. They're all scared of her. Treading on eggshells. She is a nasty women and they're all frightened. They appear on video and her channel because, to disagree, would result in emotional abuse or manipulation. This can come in the form of 'don't you want to see your Mama happy?'
I think Mark is so downtrodden he doesn't know how to leave her. He's scared of her. Perhaps he doesn't agree his kids should be exploited online but he's scared to disagree with her. I bet she's pulled the 'you won't see the kids' card.
Decorating his office appears warm, kind and loving. To me, picking the decor and items in HIS space screams control. He can't choose anything. He is just her puppet.
Don't be fooled by her. There is a sinister side to her. She believes the baby voice and gestures hides this but you can see right through it.