@RationalizedInsanity you don't? That's not how Fediverse works.
They are seperate accounts, but you can follow your Peertube account with your mastodon account and when you post a video on Peertube, it'd show up as a post in your timeline that you can boost, like, and comment on.
The comments should show up as a comment under the video and you boosting it would give it visibility to your mastodon followers.