In many Google apps and other third-party software, you see a spinning circle appear when you pull down from the top of the screen to refresh content. This pleasant little indicator is a sign that something is loading in the background, but you have permission to keep scrolling around while you wait.
Some users saw the pull to refresh animation appear in the YouTube Android app back in October. The circle's appearance had nothing to do with which version of the app you used, so there was no way for us to distribute the change to everyone. We didn't even have the animation ourselves.
By now, things have changed. We're seeing the tweak ourselves and we've heard from many of you that the animation has also appeared on your devices. The change appears to have now become widely available. If you have not yet checked, open up the YouTube app and pull down on the Home page. Yup, that's the look of YouTube fitting in with other Google apps.