Was asking the same question when reading about the Odyssey and lbry inc stuff.
In short it seems like decentralized indexer, so Peertube should be able to use it for searching content (I did not verify this).
Longer answer is that classic indexers join content metadata (file name, …) with the BitTorrent hash, this does the same thing but instead of being a single website this metadata+bt hash is stored in the distributed blockchain (so no singular entity hold this information, censor resistance etc).
The data is still distributed thru BitTorrent so it has all the stuff of that protocol like files going dark when noone is seeding.
E: also uploaders of the content can also set a price for getting the files but I have no idea how they handle people just sharing the torrents (hashses) outside or w/e
My answer is that it’s glorified DHT with metadata search.
I found this when searching for some more technical stuff - spec.lbry.com.