I've mentioned this in the past and looks like it's finally rolling out for select subscribers at first and then everyone in the coming months. Nice feature for sports.
YouTube TV adds multiview streaming in time for March Madness
YouTube TV now lets you watch up to four shows at once — if you're part of the early access release.
www.engadget.com
Two (or four) is better than one: Building multiview on YouTube TV
Early access to multiview will roll out to all YouTube TV members over the next few months.
blog.youtube