Corona beer freezing by itself?

Question

I saw a you tube video of a Corona beer freezing in seconds by someone tapping it on the table.
How did they do this? I know that someone by the name of numbfreeze was explaining this, but does anybody else know?
http://www.youtube.com/watch?v=SfkHS_58yvs

Answer 1

When you put this beer in the freezer it will cool down even below a freezing temperature.

To be able to freeze it needs something to activate the process, like banging it, or just adding 1 very small bit of of another substance.

The beer initially is in metastable form. It is still liquid but very unstable.

Answer 2

It's one of the effects of global warming. Like el nino`.