Looks interesting, but it'snot clear on how they protect metadata from the STUN/TURN part of webrtc. Potentially its use of the Multi-Party Relay that insulates peers from those services knowing anything about the peer. Some interesting points were from the article:

- Booth leverages the same INVISV Multi-Party Relay (MPR) architecture that we also use to provide Internet privacy for Relay users. Using an MPR, users’ network identities (IP addresses) are masked from the cloud server that they connect to. https://invisv.com/articles/relay

- Booth is designed to use meeting “booths”, where the booth link is randomized for each meeting. Likewise, Booth users don’t need to reveal their names to the server. ... (Note that Booth relies on browser support for Insertable Streams/Encoded Transform, which is limited to Chrome-based browsers at this time.) In addition to this end-to-end encryption, Booth also employs additional outer layers of encryption as described in the MPR architecture.