Screenshot of the comments section of a PeerTube video, showing how a reply made in Mastodon appears as a comment below the video in PeerTube.
https://media.mstdn.social/media_attachments/files/108/103/233/541/726/313/original/c28333e596368e60.png
If you're on Mastodon, you don't need to do anything special to interact with other Fediverse platforms.
Their posts will look just like Mastodon posts, and you'll interact with them the same way. You probably won't even notice you are interacting with anything outside Mastodon!
See the attached images below for an example of interacting with a PeerTube video from within Mastodon. The account used in the example is @yesterkitchen, you can try interacting with it yourself if you like.
By the way, to see what a post looks like on its home platform, click on its datestamp at the end of the post. This will open it in a new browser tab or window.
Bobinas P4G is a social network. It runs on GNU social, version 2.0.1-beta0, available under the GNU Affero General Public License.
All Bobinas P4G content and data are available under the Creative Commons Attribution 3.0 license.