mpv

mpv plays almost any local file or stream you hand it, with a bare video window and an on-screen controller instead of a library or playlist browser. Most control happens through keyboard shortcuts, and behaviour is tuned through plain-text configuration files and Lua or JavaScript user scripts.

It is closer to a power-user engine than a polished Mac front end: there is no preferences window, and the project describes itself as a command-line player. IINA, already in this catalog, builds a fuller macOS interface on top of mpv. The project's GitHub releases include macOS builds; the default build is GPLv2-or-later, with an LGPL build option described in its Copyright file.