I just don't get the point. If you can process content much faster than it was meant to be played, it doesn't mean you're learning much faster than you could, it means the novel information density is low. Any content that can be sped up that much without loss is not worth listening to in the first place. You're just skipping the trite cliches, filler, and obvious facts.
I can read fast, and I typically go through fluffy NYT bestseller nonfiction at 600 WPM. But when I do this I constantly have a sneaking suspicion that I'm just wasting my time. When I read a good book full of new ideas, I barely go at 150 WPM, but the time always feels well-spent.