@rmader My dream scenario would be to use whichever has the best base of Clapper and Celluloid, and then take the best features/UX elements from the other and integrate into the first. They are both really nice, there's no need to do all the work to port Totem IMHO, but they are both also lacking a bit, and a blend of the two could be perfect. :)
If we go for an alternative, the main requirement is surely #gtk4 / #libadwaita with adaptive UI. For distros it's probably also important to have some kind of dependency management to install missing codecs.
The language could probably be anything from c, rust, vala or gjs.
I wonder about the backend - should sticking with #GStreamer be a requirement or is something based on #ffmpeg / #mpv ok as well?
For #GNOME app folks: IMHO we need to think about what to do with Totem / Gnome Videos. It has not yet been ported to #gtk4, which is increasingly becoming an issue.
Apart from not fitting nicely UI wise, it prevents us from using the newly introduced #wayland hardware offloading (zero-copy playback) and, crucially, from (properly) supporting HDR content going forward.
I.e. we either need a port - or should consider making an alternative a core app to focus on.