Its not particuarly dangerous, but it isn't very good for the floats.
If you hit a chuck of ice at high speed it may dent the floats.
Possible to puncture. I would be suprised if this guy did not damage
his floats (a dent or two). But given a smooth surface, no ice chunks,
either hard ice or slush or even packed snow, it could be done,
obviously, by witness of the video.

Desperate men do desperate things.