[GenerocUsername]

Looked like battery packs to me. Basically just high powered fans pushing you forward, not true jet-engines or rockets or anything.

That said, adding distance would require more batteries, and that would add weight, but I would bet that the batteries are 1/10 the total weight with all the metal-housing and motors involved

[JoeAltmaier]

Batteries are about the least energy-per-kilo way of storing it - increasing battery energy would cost the very most in weight you could imagine (except perhaps a windup spring)

Liquid fuels (gas/alcohol) are very efficient. Metal-air batteries may beat liquid fuels for ergs/kilo?