His brake light needed a new bulb, and he managed to make this 12V LED bulb work in the 6V socket. An LED is a really great choice for this application since the Motobécane Moped uses a magneto ...
As an electrician, I’ve dealt with tons of broken lights, and the worst ones are outside, where water or dampness caused the lightbulb and the lamp socket to fuse or rust due to corrosion.