Probably one of the guys at Säkpluton Sjö or AMF1 (GBG) who bought themselves a Rib, and takes it on a spin.. Could also be some guys from the Homeguard.. My bet is someone who wants to get a piece of the "RIB-Tour" pie..
At 4.02 u can see that they don't use a Swedish Naval flag, but rather a civilian one. So they are not official, but I guess they have ties to the base..
Yupp.. I know.. If you check the other vids on their Youtube-page they aren't exactly stating a solid case in terms of seaman-ship.. As I said before, my bet is on guys who thinks along the lines of "Hey, let's get a RIB and start a company.. Mäklarbricka på Marstrand is pretty much a done deal.. "
I'll forward the link to some people see what happens