Marital sex just needs to be varied. If the couple won't do it together, then clearly they will still do it secretly each separately! I think this home variation is acceptable, in any case it is not as extraordinary as entertaining a large group of swingers. My wife and I once invited me to one of these, against her this clip is just sex puritanical family!
It's pretty much clear with sex, even using a condom. What is not clear is why there are two big TV sets on the wall practically right next to each other. And what's more, they are mounted at different angles! By the way, the man can clearly see how much he enjoys his girlfriend. Although to be honest she looks like a plank!