[Earth]

I seen this from multiple companies. I believe its just magnetic with some and that if you take it off the magnetic platform it will not work.

In the case o this one I believe it was being held up by some clear string like fishing line and that is when when he stepped on it that end went down and it was immediately cut out.

The Back to the future hoverboard technology just does not exist yet, and if it does it is not public yet and is still being tested and worked on.