It is a pretty cool video, but no mystery...

It's just an RC model plane made to look like a lawnmower. It probably only weighs a few pounds.

Dang now I finly know what to get billy bob joe,
The perfict gift for the red neck in your family who already has everthing .

O.K. but don't you need wings for something to fly for stability? Lawnmowers don't have wings. How is this possible? And yes, I agree, Billy Bob would be very happy with a brand new flying lawnmower.

Wings not necessarly needed. The whole body of the lawn mower acts as a wing. If you could get a good look at it standing still. It looks like a lawn mower but bet it wouldn't cut much grass.
Neat toy!

If you look closely you can see the flaps at the rear of the lawnmower, and I would guess that the "handle" acts as a rear stablizer, but I didn't see a rudder. It might not break any laws of aerodynamics, but it truly is a marvel to behold.