Using audio samples from movies ..... copyright problems?!

My pineapple express sample, around 2:30ish lol. Haven't gotten into any dramas for it. Was number 1 on aus iTunes charts for a week and even with that attention still no suits barking at my door.

http://dl.dropbox.com/u/6361630/Timeless.wav

You're the guitarist for Thy Art is Murder, right?
This is the OT section, so pardon me while I go off topic. :D

What ever happened to your original vocalist, dude? I thought he sounded weird and very unique and it worked out for your sound. The new guy sounds good, too, but I'm partial to the last one. I just hope it was for personal stuff and not "the old guy sucked." Haha
 
Back 'on-topic':
Quoting from youtube movies that aren't clips from real movies, do they still need to be credited/paid for?
I noticed that some use clips from viral youtube vids in their songs, I was wondering if there's a legal maze as well in there.