* Audio input

linux-pulseaudio builds, but fails unless you "pulseaudio --start" first,
even then doesn't allow device selection when pulse input is used as source,
and doesn't seem to actually record anything whether pulse's input or output 
is used as a source. 
 
linux-jack builds, I've patched to autostart the daemon (which I think is
expected for JACK clients anyway), but doesn't allow device selection, and
doesn't seem able to record anything.

* Video input

linux-v4l2 should be able to work with multimedia/libv4l but as usual
with V4L2 applications it will require various patching to work with
OpenBSD.

video4linux2 available via ffmpeg (see pkg/README).

* General

If you "start recording" and "stop recording" then it sometimes seems
to hang when stopping.

There are the pull requests being open, based on the code from this port:
https://github.com/obsproject/obs-studio/pull/3714
https://github.com/obsproject/obs-studio/pull/3715
