Another key point is that LBRY and PeerTube have different philosophies on how to approach decentralization. I believe LBRY uses a Blockchain for media storage, but PeerTube is more built around the concept of data federation - people set up separate sites that can then seamlessly integrate with one another by passing messages around, rather than each site having to maintain a separate copy of the same ledger.

Additionally, PeerTube is also compatible with the wider fediverse through the usage of the ActivityPub protocol, meaning that channels can be followed via a dozen or so other platforms that all speak the same federation language. Theoretically, it would be possible to write an entirely new project from scratch (in a completely different language even) that's capable of federating videos with existing PeerTube installations.

This is not to say that there's anything specifically "wrong" with LBRY, just that one approach already integrates with a broader set of platforms due to what community it was developed out of.