Witty plays a Martin O-18T tenor guitar for both the rhythm and the lead parts. I can’t tell what he has in his right hand while he is playing the lead, but it looks like an E-Bow. Unfortunately, I’m not sure, as I believe an E-Bow needs a magnetic pickup to add its violin bow effect to a guitar lead. Having never used one, I really couldn’t say for sure.
As for the tuning, it took me a while to figure it out and I nearly drove my oldest daughter crazy in my attempt. It appears that he has tuned his tenor a fifth lower than standard tuning as F-C-G-D and a step below Chicago tuning (G-D-A-E). I hadn’t heard this particular tuning before, but it really gives the guitar a different sound. Very nice.