Thing is though, making one minute of lets-play costs a lot less (time / money) than making one minute physics or crash course or you name it.

Also, I probably watch hundreds of hours of youtube every month so the amount that ends up at each channel will be extremely small 5.50 / monthlyHours * oursPerChannel isn't going to be very much in the end.

The biggest winners are going to be MCNs (Multi Channel Networks, which most Let's Plays are part of) which take another 20-30% of the revenue generated by each of their partnering channels.

If you want to support single channels, something like Patreon is still going to reign superior in terms of actual money received at the other end.