The new feature is for FAST, which is a type of IPTV stream. Imagine something akin to a TV channel guide, like Samsung’s and Roku’s built in streams.
And the “ad supported” bit is misleading; The channels are supported by ads, and run them as part of their programming. It’s not VLC showing ads before you’re allowed to stream the video, like YouTube. Just like regular TV channels, where they have commercial breaks.