This looks like the Sealegs system. They've been doing this on RIBs for some time. The system uses hydraulic motors and a powerpack. You ave to have electrical power for the power pack and AFAIK it only runs for about 5 minutes at a time (due to heating). You can use it to launch and retrieve the boat, but it's not like you can drive the boat down the road.
There is one of the Sealegs system RIB's in the South Puget Sound near Olympia. I have watched them cruise up to the beach, and then drive up the shore and into a garage next to the house! I think of them each time I launch or retrieve!