Setting mpv as "default application" for videos breaks mpv's normal behavior
When mpv is set as a default video player - selecting multiple files and opening them in mpv opens multiple instances of mpv, one for each file (unexpected behaviour).
When totem is set as default - selecting multiple files and opening them in another application (mpv) opens single mpv window with a playlist, where all selected files present (normal behaviour).
Somehow gnome-control-center breaks normal behaviour of mpv. The bug only affects nautilus (no issues in thunar and nemo). Originally reported here (i'm not sure if it's fedora bug or upstream), more info could be found here.
Maybe it is related to mpv.desktop file, especially these lines:
TryExec=mpv Exec=mpv --player-operation-mode=pseudo-gui -- %U
Full file can be found here.
Fedora 28, gnome-control-center 3.28.2.