I ended up watching it before work this morning. Very cool show!
He broke down each detail and since laser light would simply go on forever, not stop at 3' from the hilt, another method would need to be used. Plasma, such as that used for welding, was the answer. Except to control it, and be able to duel, some sort of containment would be required. Luckily, plasma can be controlled with magnetic fields, and for dueling, a high grade ceramic can withstand the incredible heat, yet also hold up to dueling.
The most incredible to me, was the power source. Nano tubes! Trillions of nano tubes can fit inside the hilt, and could store all the power required to generate the energy required for a 3' plasma torch. A fan in the base of the hilt would suction oxygen to the emitter where it would basically work just like the welding torches - but larger.
Highly recommended if you can find it on your cable guide this week. It should be replaying 3-4 more times until the new episode next Tuesday.