Although I am an archeologist...? (Although I assure you that I am an archeologist...)
Source: https://www.youtube.com/watch?v=3xs-XWk_oQA 0:23
In this case, the なんです functions exactly like
んです (which isn't used here due to grammar restrictions)
So basically, he wants to say 'Although I am an archaeologist, I do not wear a hat like Indiana Jones'. He assumes that the viewers might have the misconception that all archaeologists wear hats, just because Indiana Jones (who might be the only famous archaeologist they know, and hence the misconception) does.
In other words, that archaeologist thinks that (to the general public) being an archaeologist implies that he wears a hat like Indiana Jones.
You may read this page for more examples on ~なんです・んです: