This was when the first video came out, like 5 years ago - Harry Potter and the Philosopher´s Stone. Unfortunately, Daniel Radcliffe couldn't be there.
Ok, this is for the americans wondering why I wrote "Philosopher´s Stone" and not "Sorcerer's stone".
"Philospher" = The original, British title.
"Sorcerer" = The American title.
They had to change the title; they were worried that Americans wouldn't exactly understand what a Philosopher is, given that it isn't exactly the same in the US as it is in England.
This has though led to criticism as the titlechange may have insulted the American's intelligence.
Rowling opposed that idea. But since this was her first book, she didn't dare to stand up to the American publisher.