because they made a macOS realease on Aug 16, 2021
---
not very usable though...
it needs their own mpv build with some modifications to allow video playback inside SMPlayer's window, but that build doesn't support Vapoursynth, so you have to switch to the Homebrew's mpv
you CAN do this (Preferences -> General -> Multimedia engine = "other" -> /usr/local/bin/mpv), but only with Preferences -> General -> Video -> Output driver = "gpu"
in which case video will open in an _external_ window