The man does not lie. I made a wizard to test this.
http://www.youtube.com/watch?v=xqJPPLYgbaQ
I tried to make the quality as good as possible without taking a year to upload, but in case you can't see the numbers:
The duration goes from 0:42, to 0:36, to 0:30, to 0:24, and then poof, it just disappears.