Maybe not controversial but just talking about portfolio companies or commenting on them directly can be risky when you have a big fund and LP's to deal with.
When speaking at an event with 1000+ people, anything you say should be considered public. No more risk from this than blogging.
Agreed but there's a difference between being on video and someone writing about your talk. Some people just don't like the pressure of a talk being recorded and prefer people to write about the general talk if they want to write about it.