You have a couple of diferent options: You can try and search the video directly via your peertube instance.
https://videos.elenarossini.com/w/64VuNCccZNrP4u9MfgbhkN
and comment, upvote, down, etc...etc...
If you want you can also navigate to the respective channel at that point and click subscribe.
You can also, alternatively, search fedifuture@videos.elenarossini.com on your search bar and the channel should pop up.