I hear the top note(melody) well, but I can almost never get the chords. I certainly cant figure out this left on this song because of the speed. I would really like to sound like this. Anyone able to describe what he is doing with his left hand?

http://www.youtube.com/watch?v=cxLXZQQJElw

for the most part, that's a common rock pattern. In rock, they like to play 5ths.
So for example, he'll play C-G twice, then C-A twice.
Then here and there, he'll walk up in octaves.

Yes, that's a boogie woogie piano pattern that Jerry Lee Lewis played a lot of too (5th 5th, 6th 6th, 5th 5th, 6th 6th). And sometimes he is just playing an octave repeated in eighth notes

Check out this youtube instructional:
http://www.youtube.com/watch?v=m3_zRmb-0u0

Your pattern might be close to one of his "shuffle" patterns.