Video is choking hard because all the hardware accelerated options are not up to the task on OpenBSD, at least not on a Radeon 9200. The AltiVec enabled FFMPEG enables the software accelerated xvideo using AltiVec instead of your GPU and that can play 360p YouTube videos on high end G4’s.
If your up to it, I recommend uninstalling mpv, uninstalling the standard FFMPEG if it is installed, installing the AltiVec FFMPEG if not installed, then compiling mpv in ports from source. It may work, may not never tried. I can’t remember if it will use its own internal FFMPEG or if it will use the one currently installed.
It will search for ffmpeg but since only the altivec flavor is installed from ports, it uses that one.
Now compiling mpv from ports ...
Whilst after 4 hours of struggling with flexget, showrss magnet links and rtorrent on my OBSD 6.7 Thinkpad, the Thinkpad is now using a showrss Python script to use aria2c downloading ShowRSS magnet links
Next up on the Thinkpad, dunst notifications from aria2c running as a daemon using notify-send without those bloody RPC calls.