I contacted the artist, and he kindly provided the Blend file. Unfortunately, he's not responded back to the questions I asked him. this file was made two years ago and works perfectly.

Can someone PLEASE take a look at it and tell me how he got the track to STAY on the Path and how he got the wheels to rotate automatically as well?

http://infin3d.servebeer.com/taxonomy/term/104

Here's his YouTube video:
http://www.youtube.com/watch?v=vDhHyaK76OY&feature=channel_page

Here's my Original file (Before coming across the above artist's video)
http://www.filefactory.com/file/ag8gfc2/n/TankTrack_SHARE_rar

You can see that the track keeps coming off of the path here:
http://www.youtube.com/watch?v=TpDNQtf84hk

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PLEASE don't bother providing a tut to the soft Caterpillar approach. It's WAY TOO complicated and I get lost in it far too easily. The above method is clearly MUCH simpler and works just as well.

Thanks