Ever wish you could use the YouTube app to watch a video without it showing up in your watch history or tainting your personal suggestions? Basically, Chrome's Incognito Mode, but for YouTube? Now you can. While it's been in testing for some months, Google is now rolling out Incognito Mode for YouTube widely, and it works just as you'd expect: nothing you watch goes into your search or viewing history, and you can easily pop in and out of Incognito viewing. Here's how to use it (and why you might want to).