acrylic two-part adhesive.
 

I bought the DVDs for the "MG is Born" show and watched it last night. In it he used a two-part acrylic adhesive to bond body panels to supplement the welding. He did not show the brand name or explain very clearly what it was, he did show that it was in tubes like a caulk gun with a nozzle that mixed the two parts as you squeeze it out.

Anyone have a clue as to what it was he used?

This sounds like some thing simular not saying it is the same stuff though....

http://www.permabond.com/en/en-epoxy.htm