Hi, Will!
I totally agree with you! This collection of "Where The Hell Is Matt" is one of my favourite videos! It cheers me up in a way you can't imagine! I first came across one of his videos six months ago. When I feel under the weather, I take a look at these videos, which are really effective! (I wish I could dance like him...) 
Will, this is an interesting question, what our favourite YouTube video is... I've got lots of options in my list, so I'll figure out where I shall start. *LOL* 