You have far too much time on your hands, this thread was started 3 days ago and yet here you still are. Checking back continously to see if others agree with you and put your two cents in. Sure, there will be many who agree with you, but it all stems down to the point, what on Earth has it got to do with you? How this young couple chooses to live their life is of no concern of yours, they're not affecting your life in any way, infact, they probably didn't even know you existed until they saw this thread.
My parents are in their mid fifties and I'd be both mortified and embarrassed if I found them criticising a young couple they came across on YouTube because their views on how they should be spending their lives differ from theirs.
I would also like to add, our time on this planet isn't infinite, tomorrow isn't guaranteed for any of us. I sure as hell wouldn't want my last day on Earth to be spent criticising others or offering "advice" that ultimately won't change anything. You live your life, focus on that and above all, try to be happy. This couple seem to be doing just fine and will make mistakes along the way just like the rest of us. Live and learn, that's what it's all about.