Hm... those screens have no internal speakers. So why are they (or at least the one with opera on it) shouting "PLANESCAPE" right now? Makes no sense!
Well, of course, the DM is always right, and the players always have the right not to play, and some interplay between the two is required, but the players should not be able to order the DM around any more than he should call all the shots all the time with the players being mere spectators.
I think the idea of going Discworld* on the campaign and the players' assumptions is a good one. What's sauce for the goose and so on! If it turns out that they want the world to be open-minded about them while being allowed to be prejudiced against everything else, it's your responsibility to educate them a bit!
*For those who don't know the Discworld, one of the best things about it is that Terry Pratchett took all those staples of fantasy - its stereotypes, its assumptions, the big stories, and so on - and shamelessly applied some Real World to it: Thinking it all through and looking where something like that would lead if actual people were involved. Not logical or consistent, because the Real World isn't logical or consistent, but just like you could imagine things going if they happened here and now.
Some examples:
The Discworld has the stereotypical dwarf - a short fella about 4 feet high, as well as wide, wearing heavy armour, carrying an axe, drinking, looking for fights, thinking about gold all the time (they don't love gold, mind you - they only said that to get it into bed!).
But that's just the "city dwarf": The dwarves who decide to leave the ancestral mines to go to the Big City Ankh-Morpork. Sensible guys and gels who were the very image of politeness back home start acting like drunken thugs as soon as they go away from home and into the big city.
You also have "blue ribbon" vampires who swear off blood, meet every week to tell the Group about how they fought against their addiction.
Magic isn't the mystical fire-and-forget force you know from other worlds: Due to the universal law that to do something you have to put a specific amount of effort into it, no matter how you do it, it takes about the same amount of time and effort to memorize a spell to levitate a rock 10 feet up onto a ledge than it would take to get the stone up there the old way (it used to be different, back when Sourcery, the source of magic, was about, but after that nearlly ripped apart time and space, the laws of magic were changed).
Also, just because it's magic doesn't mean that you can ignore all the natural laws. If you teleport something from one place to another, you'll have to take something of about equal weight back. And, of course, the calculations have to be correct, or the subject will be history - or, rather, geography. Those calculations include different rotational speeds depending on how far away from the hub you are. If you teleport from the rim to the hub, you better land running!)