Hmm, so it is actually a gasoline engine driving two ducted fans. Not exactly what I think of when I hear the term 'jetpack'.
Unless some serious breakthroughs in physics come to pass, and equally serious breakthroughs in engineering happen that can implement those breakthroughs, you'll probably never see something the size of the well known Bell "flying belt" style jetpack that can fly a human being at something approaching "car ranges" at "car/motorcycle speeds"
The Bell-style jet-packs seen in movies, and stunts at sporting events etc. only have a flight time of like 30-60 seconds, and use nearly pure hydrogen peroxide, explosively catalyzed over a platinum mesh to produce the thrust. There's even more energetic compounds, but they're even more dangerous and unstable.
Any power source, be it chemical, electrical, nuclear that you could possibly conceive of that would carry a human into the air and move him a tens of miles per hour, for even say 50 or 100 miles, and packed into the same footprint of the Bell pack also would make a pretty decent bomb.
It's just too much energy in too small a space that's needed to do the work all via direct thrust. Helicopters and airplanes that instead use the energy to push off of the air with rotors, propellers, and wings are many, many times more efficient.
