Here are a couple tips to improve the usability of peertube.
Use sepiasearch when finding new peertube instances and videos. Some browsers such as firefox allows you to create a shortcut for searching
Subscribe to channels through your most used fediverse account. Then it will pop up in your feed and it’s easier to comment on videos.
Are you trying from Mastodon or Peertube ? Maybe the instance owner blocked federation with an instance ? For Mastodon I like using the search box, with the user info showing up in the middle and a follow button, instead of going for the option of another browser tab open for a remote follow.