Impressive?
"lanyards used at the conference, ... that contains a light and can be controlled from without. With impressive results, as the video below shows."
I hope that was sarcasm... surely an indistinguishable result could be obtained by a random flasher in each one? Wake me up when each one can establish its location accurately enough to show a readable message across the hall, and they are still cheap enough to throw away in a lanyard.