https://www.phoronix.com/forums/forum/phoronix/latest-phoronix-articles/1517933-cosmic-alpha-5-desktop-brings-cosmic-media-player-as-default-vrr-updates?p=1518084#post1518084

for the media player, quoted from mmstick (phoronix.com)

A video player is probably the easiest app to implement because it’s based on the iced video player widget. It’s just a matter of porting it to COSMIC. And there’s no reason not to add a video player to the core lineup if it can be done. Every OS has a default system video player.