are my ears going on me?

So I thought this would be a nice song to try and work out in 2 finger style to give me a break with clawhammer. It's good to take breaks right?!
It seems Clifton is sliding UP the neck at the very beginning of the song and throughout, but it sounds as though he is sliding to a lower note!
Are my ears deceiving me? I just can't figure out how that slide up is creating that sound?

Any ideas?

http://www.youtube.com/watch?v=hNTRx45ilGM&list=PL07R2cMG4rBzd9kOCmHy5JcV8AIDqiq9b