I've never understood...
....why things like this don't use video conferiencing? Working at a local government IT department for several years, even that department still doesn't use such tech and forces it's staff or managers to travel miles to other sites. It's stupid.
I still think Mark has anxiety issues when it comes to doing talks like this. He's OK and promoting Facebook but I don't think he'd be good at being questioned hence he never agrees to these talks.
I still say, if you use Facebook that is a service that cost a lot to run but you're using it for free, you can't really moan what they do with your data.