To see it in action:
Crust.piefed.social (the Piefed development instance)
Not all instances implement it yet, I guess it depends how often they pull from the dev branch
Example of search for 'movies'
What would a Feed/multicomms' actively weekly users even be? An aggregate of all the comms weekly users, or just the highest one? Or does Piefed go through all the comms and collect the unique actors (God, that would be an expensive operation)?