At one time, visually recording a maintenance task for later use (e.g., training) was hardly worth the effort. It required using a film camera, getting the film developed, and then getting people into a room to watch the film. But today, you can make a decent recording with an inexpensive digital video recorder (DVR). Or even a smartphone. And you can make the recording available to anyone with an MP3 player or browser. Especially with the younger generation of electricians and maintenance techs, a how-to video helps people understand what the maintenance task entails and how to do it right.
Training tends to grow stale over time. People forget some important details, and then begin altering the procedures. To prevent this, it used to be necessary to put people through classes they'd already taken. But now you can cycle individuals through refresher self-training modules that include watching video clips of maintenance being performed. Be sure to edit or record in a way that highlights what's important, so viewers don’t get mired in mundane detail.