FYI

I started a list of conventions/conferences with accessibility policies a while back At the Geek Feminism Wiki.

Anyone can edit this wiki. If you know of cons I can add, please suggest them!

I would just like to say that doing vid show warnings / content notes is actually quite simple.
Here are some examples:

Vidukon
Festivids

ao3 dot org

I'll have more to say on this later. Context if you ask for it.