It doesn't claim the 35.5 kts were done on the footage you can see!!! This spot can be a very very fast spot depending on wind conditions but also very choppy as can be seen on the video.
These guys are at least as good at checking GPS tracks as gpsspeedsurfing. I believe they got all the tracks from the Canal, it must be posted somewhere on their forum.
Btw a *board Go is nowhere near a Formula board!!!