What is Blizzcon

So I have been posting so many different things about Blizzcon...no I'm not done yet,to much to talk about... but someone reading all of these posts may still be wondering what the hell Blizzcon is. I've been searching for this video clip I saw at Blizzcon where I'm in the BG... even though you can't see me, I'm there! lol. It still hasn't been uploaded, so instead, I have found the below video which gives a pretty good feel for what to expect.