The scenes in bed are short- just a few seconds of footage and no sex- just sleeping- until the alarm clock goes off or someone gets a phone call- that sort of thing, very mundane, but still ineresting to see on TV.
As for sharing a big bed in real life... I love it. Of course, it's not for everyone, but worth a try at least once or twice.
A few years back, my wife and I were in a quad relationship with another couple, and we always shared the bed. It was pretty great- lots of opportunity for closeness, affection and bonding- not to mention the sex- fantastic, especially if you're a little voyeur/exhibitionist inclined. Of course there are practical matters, like, as you say, getting up to pee etc., but it's really no problem. You learn to adapt. And if someone was really having a hard time sleeping, they would just go to the other room. (and sometimes someone else would follow.
Sharing the same bed really fits my ideal poly relationship- an intimacy shared. I'm hetero, (I don't say straight, because I'm clearly bent
) but sharing a bed with a another man who is having sex with my wife is a profound experience.