BTS is a great idea both for helping us understand the work put in, getting to know performers better and promoting scenes.
I think it would be smart to post links to scenes mentioned and maybe do a little promotion. Let actors and directors talk about a scene, what they are trying to achieve and how they felt about it. BTS could provide more value with intent slightly shifted from revenue creation towards promotion. I think 3 tickets would be fair. At 4,5 tickets I expect a porn scene not a promotional trailer.