Just checked the website and it says it will be at the Anaheim Convention Centre, between the 1st and 3rd August.
VidCon is much much bigger than London MCM Expo and has tons more YouTubers than you would get at MCM like DanIsNotOnFire, Tobuscus, Daneboe, EpicMealTime and loads more American and British YouTubers who usually all do a panel together. I know last year TomSka got partnered with Daneboe, Tobuscus and another guy I didn't know.
This the the guest list so far -
[link]But yeah I'd definitely go they have music performances and tons of other stuff!
Hope I can go in the future