Video players is an interesting conundrum - some are feature pack, some are “light weight” but are divorce of deemed useful stuff.
Celluloid formerly gnome-mpv is our current video player. In the next release “1.0” it will be a libadwaita app.
XFCE ships parole - very lightweight in the same category as celluloid arguable.
GNOME Totem is a libhandy based app - more feature packed than most.
Then there are the Qt based apps like VLC and the rather garish looking smplayer.
Totem and Parole are my first thoughts - there is a route map for GTK4 version of Totem but seems to be blocked by quite a few things. So maybe swap to Totem for the foreseeable future but may need to reconsider