The system uses lasers that it splits and focuses. They fire the split, focused laser into a chamber of hydrogen atoms, and it is actually enough for fusion. It was probably an exaggeration, but I think they said they could power the laser with a 9V battery.
The energy output from the reaction was enough, they said, to power the entire Earth several times over, but it lasted for the smallest fraction of a second, so it could not be properly harnessed.