Not That Funny Tusk Doc
 

Look closely at about 1:50. Who else is on stage? There is someone clearly to the (our) left of Lindsey and then there's something else to the right further back that does or doesn't look like a person lol.

I am fairly certain the person to the left is a camera guy. Kind of odd because I thought the entire performance was filmed from the audience. However, there's an alternate The Chain out there that has some camera shots that lead me to think that they did a couple of shots on stage during the performance. Kind of like Rosebud if you notice the camera guys actually in the band's "personal space" if you will. Ok, so maybe I just answered my own question lol!

The other thing to the right I have no idea what it is. I thought maybe it's John?