Since this engineer is playing western/country music fingerstyle, this banjo is supposed to be a five string, with the fifth string being a bit shorter to support the music with a little bit bass.
Five strings are in the most cases the only banjo's from the banjo family who are supposed to be played either with just your fingers (fingerstyle) or fingerpicks. This (especially in case of fingerpicks) gives the music the sharp *doing* sounds as heard in most western/country music.

The banjo depicted here is either a tenor or a plectrum banjo (both containing 4 strings), which wasn't uncommon around the 70's-80's, but was rather uncommon as a western/country banjo and was more commonly (maybe always) used for jazz/blues. Which as the name might suggest are played with a normal pick.

Anyways, great taunt, I'd only suggest importing a five-string model of the banjo as well (like a variant or something) of make it so it seems like he is holding a pick. Just to keep te music freaks like me from getting butthurt :).