It's pretty close while the bike is upright and the gps has caught up. Once the bike is tipped onto the side of the tyre, using a smaller diameter, the speedo reading is marginally higher than the "real" gps speed. Same reason you can hear the engine revs climb a fraction when you are on the edge of the tyre.
Liked that video too, thanks Hammy or Woody or ..........? One observation is the cold tire temps 32/37 seen on screen, wish that would have stayed on after the laps. There is a tire inflation pressure argument going on in other places of this forum.
See if you can spot the discrepancy between the stock speedo and he GPS speedo in the corner of the frame.