From the video:
Range: 125 miles all electric
500 miles with hybrid system (electric + conventional turbo prop)There are maybe some advantages to a hybrid system.
The higher reliability of electric.
Losing an turbine engine doesn't mean asymmetrical thrust. Plane still flies normally.
Losing an engine on takeoff you still have full power.
Electric motors spin up faster than turbines. Which means faster throttle response. Which you need when hit with a wind shear on landing.
Take off and landing under electric power means much less noise.
Efficiency, you can increase the number of props or fans to get a much higher bypass ratio. Worth noting the plane in the video has four props.
In the video he explains that the goal of the hybrid system is mainly to be used when for some unexpected reason the airplane cannot land at its original destination.