There are three new features available to Premium users. One on iOS only allows you to watch and seek within videos directly from the home screen, another lets you search for videos using your voice (web only) and the last helps you filter by topic in new languages: Spanish, French or Portuguese. All of them have time-limited access.
YouTube Premium costs $11.99 per month for ad-free viewing, YouTube Music, background play and other features. The Labs program probably isn’t enough to tempt anyone subscribing, but it could be a nice perk for loyal users.