You have to separate 2 different terms. THROW and INCIDENCE.

Throw is how much the surface moves up or down. Incidence is the angle of the surface to the surrounding flow.

For a first flight of a canard model which has elevons I'd set the throw to zero. You can increase them later on and get the right values. Meanwhile you need to set the elevons right.

The incidence for the canard should be positive. When you look at the video they seem to be at a negative incidence. This coupled with a very probable aft C.G. would cause exactly what we saw: a very unstable airplane. I'd say fix the canard with a positive incidence of 1-2 degrees and move the C.G. 5 cm forward and try again.

BTW. The original Lavi did not have the canards functioning as flight controls. They had 3 positions. Takeoff/landing was set at a positive incidence. Cruise was set at zero or a slight positive angle. Maneuvering was set at a negative angle. This was done in order to achieve different stability modes with the airplane becoming less stable as the angle lessened.