You only need a Peertube account – and the app, if required – if you’re a content creator and want to upload your own videos. You can watch videos without needing any account at all, either in your browser or on your mobile using an app, such as the Peertube app or NewPipe. SepiaSearch offers a comprehensive video search (covering a large number of selected instances).

If you want to subscribe to channels, watch, share or comment on videos in the Fediverse, you can do so from your Fediverse account, i.e. from Friendica, Mastodon, Sharkey, etc. You can also subscribe to Peertube channels and watch videos using your Lemmy account. I’m not sure, though, if all the features are available with Lemmy.

[–] Auster@thebrainbin.org 3 points 23 hours ago

Depending on the service, you don't even need an app. The instances' sites can usually run fine on browsers, and when they don't, Lemmy, Mastodon and the sort can usually play the videos embedded.

[–] Kierunkowy74@piefed.zip 3 points 1 day ago

I’m not sure, though, if all the features are available with Lemmy.

They are on PieFed.

I tried to subscribe to a PeerTube channel on Lemmy, but it looks that it stuck on "Subscribe pending". However, copy-paste of a video URL works, and I was able to watch and comment the vid using Lemmy.