Yeah, experimentation with new ideas like blackface and rape jokes.
I think the main issue with arguments against is that they rely on some black and white vision of the world (also ignoring that you can have places that aren't "safe spaces" to do your experimentation). Darwin would not have been limited by safe spaces. But hey, maybe KKK recruitment would.
The students were arguing about the FUNDAMENTAL criteria of what should be allowed to be expressed. If something offends people, that's not acceptable. So, this criteria is not limited to only "new ideas like blackface and rape jokes"- it's anything that is considered offensive, and that's why it may discourage experimentation.
I don't think one video is any more than an anecdote, not representative of all these people doing all these things at all these colleges nationwide.
Can you give me sources that exemplify supporters of safe spaces who aren't fundamentally against shaming any idea that may offend people?