Disappering David

I know this is old for this thread, but I noticed something odd in the Midland Grand Live. At the start of the show, you see David Bull, Richard Felix, and David Wells sitting on the couch. But on a later shot of the couch, David is nowhere to be seen, and does not appear at all during the investigation, tho he is listed in the end credits as "Regressionist". Now comes the weird part: I was discussing this item on the PN website I belong to. Someone posted a clip of the opening of the show,and somehow David has morphed into Ciaran, who was not even on this Live! Now some of you might think I have bad eyesight,but I know it was David. Ciaran was wearing his usual suit and tie, something David never wore on a show. David was wearing a long-sleeved shirt. So I don't know what's going on here.