Camera under plexiglass effect

There's something I'd like to know and that always intrigued me, the crane camera that goes up from under the plexiglass, in the U.S. version of Millionaire. That happens generally after a commercial break. What intrigues me the most is that you can't see (well, I personally can't apparently) any opening in the plexiglass that could make it possible or it is very well hidden. That's a little detail that drives my brain crazy ! Also, I don't think another of the +100 countries in which the show has been sold does that, huh ? Is there a trick or something ? If anyone knows how this effect was done, don't hesitate express yourself then. You know, for my "Millionaire" knowledge. That could perhaps be something ridiculously simple, well... I guess I don't know.

See what I'm talking about in this clip: 



Thank you in advance for your responses, 
Amillionaire