The largest Brazilian Mastodon instance, Ursalzona proudly displays hammer and sickle in its favicon and a logo of its admin account.
its community was probably tied up in discussions who to deferderate from next
Seeing Ursalzona admin's pinned thread - you nailed it.
I did not check Bluecast, but Bluemotion videos appear on Bluesky as links to page of that video on Bluemotion
And it looks that Bluemotion will not attempt to compete with You/PeerTube: the creator plans to end the service as Bluesky started to support video posting
Video platform (like FediMovie): https://www.bluemotion.app
Audio streaming: https://www.bluecast.app
https://lemmy.com is actually a thing... ;)