Music videos have been part of the Apple Music service since its inception, with unlimited ad-free video playback included in the monthly subscription.
The updates take the content that was always available and make it more prominent with recommendations and continuously updated editorial, akin to the New Music page for singles and albums.
Users could always make their own playlists of music videos but now Apple is tailoring its own for customers to play and subscribe to. This feature will be especially useful on Apple TV, now you can simply setup Apple Music on your TV to play top songs with the accompanying videos.
It'll be interesting to see how personalized this section will be over time. Right now, it's primarily focused on exclusive videos and curated playlists (such as the new Today's Video Hits and The A-List: Pop Videos). One of my favorite aspects of YouTube is how its front page can reliably recommend new videos based on my music preferences; I wonder if this Apple Music section is going to do the same, either via personalized suggestions or push notifications for new videos.
(Something else I would have liked to see for video playlists: right now, if you start a playlist and enable Picture in Picture on iPad, the floating video popup closes as soon as the current video ends. I'd love to see a persistent Picture in Picture mode that remains enabled throughout an entire video playlist.)