YouTube has effectively doubled the quality of videos that it can support, raising its frames-per-second allotment from 30 to 60 FPS. This is an especially big deal for video gamers who like to upload high-quality video of their gaming, as the shareable YouTube clip much more closely matches the quality of live gameplay.
This was expected -- YouTube announced in June that this move would be coming as it geared up for other improvements on the site, such as support for uploading and watching streaming HD footage and enabling (insanely high-quality) 4K video. The new 60 FPS playback feature is only supported if you're using Chrome, Internet Explorer, Safari or a specific build of Firefox called "Nightly."
This move is an important one if YouTube has any ambitions to compete with Twitch, the $1 billion Amazon acquisition that lets gamers stream their live video game experiences to all who want to watch.
Users who uploaded 60 FPS video before now saw their video playback restricted to 30 FPS. YouTube is re-rendering these videos for 60 FPS playback. Any videos uploaded at the higher frame rate from now on will be instantly available at the better quality.
Here's a sample gameplay video of Mario Kart to show off YouTube's very smooth and impressive 60 FPS frame rate.