Being able to record your camera's electronic viewfinder might not be the most pressing issue for a lot of photographers and videographers, however it can be quite useful. If you're filming a YouTube video or you simply want to demonstrate something behind the scenes, recording your EVF may help illustrate your point far more effectively.
A recent video from Matt Granger discusses how you can do exactly that using the Atomos Ninja Flame. The Atomos recorder also allows you to record your screen from several other cameras too including DSLRs from Canon and Nikon.
In my experience, filming a camera's EVF has been a little tricky at times. The quality is never great because you lose too much of the resolution due to cropping and if you get too close you start to see pixels. Other than that I feel it looks a little amateurish and I'd much rather have a proper feed from the viewfinder itself.
Coincidentally, I'm actually working on a video right now that would benefit immensely if I record the viewfinder. For that reason, being able to record exactly what you see using a recorder is very useful to me and I'm genuinely thankful that Granger put this video up. Admittedly, the Atomos is not the cheapest method so, for now, I may just need to put up with using a macro lens to film the viewfinder.
Check out the full video to see how this works.