I think some of them are True Believers. I think others manage to go along with it and believe it by being very careful never to examine their beliefs too closely because there's a part of them that suspects that asking themselves real questions might trigger major cognitive dissonance.
The essence of doublethink is never to take the risk of thinking things through. They know that men and women are absolutely identical and interchangeable and that gender is just a social construct. They know from their encounters with reality that the differences between men and women are profound and obvious. There's no way to reconcile these two ideas so they simply shut down their minds.
You can see the mental struggle going on in their minds in that video. Lots of nervous laughter.
If they ever find themselves in a situation where they encounter lots of people who don't believe this liberal nonsense their liberal beliefs will start to fade. Eventually reality will triumph. Of course our whole society is now structured in such as way as to make sure that young people never ever encounter lots of people who question these crazy liberal beliefs.
I don't have much to add to that, except to reinforce my reader's point that the system relies on maintaining liberalism as an intellectual orthodoxy. That's one reason why I think it's important to present to young people an intellectually serious criticism of liberalism.
There's one other issue I'd like to raise. I've noticed many of my female peers saying that "they don't take themselves seriously". This could just be their way of saying that they're not stuck up or pompous, or that they find it best to let go of egocentricity in order to live well. Perhaps it expresses something about womanhood. Even so, I'm not sure that people in traditional societies would have said such a thing. If you believe you are made in the image of God, and that your manhood and womanhood connects you to significant masculine and feminine virtues, and that you have important duties to self, family and community - then who you are, i.e. your "self", does matter.
What concerns me is that if liberalism teaches people that we can define our "self" however we choose, to the point that we can even choose to swap sexes, then the self will become thought of as just an arbitrary, self-chosen thing that we could just have easily made something else. Why then would the self be taken seriously? Perhaps that is where it all ends.