If it was THIS one:
http://www.youtube.com/watch?v=T_Q5EawYkm8
don't do that, except as a last resort -- you can shatter PVC lines that way!

This one is OK,
http://www.youtube.com/watch?v=jiL-pFEhWf4
but only applies to a specific set of circumstances. Ironically, the sort of problem here, is just the sort of situation that can lead to a shattered pipe using the techniques in the first video!