I recently worked on creating an xdg-app bundle for GNOME Videos, aka Totem, so it would be built along with other GNOME applications, every night, and made available via the GNOME xdg-app repositories.
There's some functionality that's not working yet though:
- No support for optical discs
- The MPRIS plugin doesn't work as we're missing dbus-python (I'm not sure that the plugin will survive anyway, it's more suited to audio players, don't worry though, it's not going to be removed until we have made changes to the sound system in GNOME)
- No libva/VDPAU hardware acceleration (which would require plugins, and possibly device access of some sort)
As we also have a recurring problem in Fedora with rpmfusion being out of date, and I sometimes need a third-party movie player to test things out, I put together an mpv manifest, which is the only MPlayer-like with a .desktop and a GUI when launched without any command-line arguments.
Finally, I put together a RetroArch bundle for research into a future project, which uncovered the lack of joystick/joypad support in the xdg-app sandbox.
Hopefully, those few manifests will be useful to other application developers wanting to distribute their applications themselves. There are some other bundles being worked on, and that can be used as examples, linked to in the Wiki.