"What happened" to it? You're LOOKING at it, right now!
PeerTube builds on top of the Mastodon / ActivityPub network, which is Decentralized Facebook.
In effect, this is showing the network effect of the new open-source / federated protocol. It can be extended to host videos over Bittorrent over WebRTC through the Web Browser (all port 80, no configuration, Javascript clients only), while publishing over the Mastodon / ActivityPub federation.
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I think there are some legitimate privacy issues with regards to Bittorrent over WebRTC (public publishing of IP Addresses and such), but as long as its a configurable flag that individual servers can turn off, then the federation can grow.