So Eventbrite asks for a 'written notification' after you've setup instead of using an opt-in setting during setup, dirty fuckers.
Not that I'm saying you should ignore this story - this is clearly a terrible move on EventBrite's part and the clause should be scrapped.
You could see them eventually either monetizing this content through advertising... or a SaaS subscription for all the people who couldn't attend a particular event.
Can also imagine that this might make the speakers/presenters less free-er to express themselves, knowing their content will be re-corded in perpetuity and can be used or mis-interperpeted against them at any point in the future.
Basically this is a clause that "Nobody who makes a living selling their words, music, etc. should ever agree to participate in any event organized using Eventbrite."