I'm a fan of Chris Smither's music. I have several of his CDs and was lucky to see him live at the "The Hardly Strictly Bluegrass Festival" while I was visiting my sister in SF. I notice in the above video that he is wearing a soft cast on his fretting hand... probably for carpel tunnel syndrome.
Here is one of my favorite Chris Smither songs. If you watch his fretting hand on the opening chords you can see where he makes an almost impossible stretch while keeping his thumb anchored on the low bass string! Check it out:
Yeah! It looks like he is double or triple jointed!
It may be one of the reasons he is wearing a soft cast on his fretting hand. Years of playing stretched chords like that will take it's toll. IIRC, Leo Kottke had wrist and hand problems a while back and had to undergo physical therapy and alter his playing position.
We've seen him play in a few small venues over the years. That board that he taps his feet on is a big part of his sound.
One show we saw consisted of a three-person song circle with Chris, Jorma K., & Patty Larkin. At one point, the three of them began a song together, but Chris soon stopped playing his guitar and just sang harmony while Patty & Jorma soldiered on.
After the song ended, Jorma turned to him and asked "What, can't you play in G?" LOL
I think Chris was simply enjoying what he was hearing the other two play, and chose to sit that tune out. Funny, nonetheless.