If I understand it correctly, as a PeerTube viewer I'm not only downloading the video, but also sharing it. Before I watched it.
This is a problem in countries where uploading copyrighted and illegal material has strong legal consequences (so I'd not want to share a video before I watched it fully so I can at least can see it doesn't have any obvious illegal content)
The viewing-is-sharing model is indeed a problem of PeerTube - and, I'd argue, of any decentralized network based on a P2P mesh. But it definitely alleviates the content distribution asymmetry problem - by spreading the load on the viewers small/medium instances can afford to scale up much more easily.
You can alleviate the problem by browsing some "borderline" profiles/instances with Tor/VPN though, or even just disable the "Help share videos being played" setting from the profile settings.
This is a problem in countries where uploading copyrighted and illegal material has strong legal consequences (so I'd not want to share a video before I watched it fully so I can at least can see it doesn't have any obvious illegal content)