On Windows, plugins are shipped with Aegisub now and loaded from
aegisub_vs.py, so user plugins installed out of Aegisub are more
likely to just interfere with that (like when the user has an
old version of libvslsmashsource installed).
So this option defaults to off on Windows, but to on everywhere else
since VS plugins aren't shipped with Aegisub there.
Note that this option only disables autoloading of user plugins.
VapourSynth loads system plugins no matter what.
This became necessary now that more providers were added. Providers can
be proritized for certain file types (e.g. .vpy files will always be
opened with VapourSynth), and when the default provider fails on a file,
the user will be notified and be asked to pick an alternative provider.
Since FileNotFound exceptions don't abort the provider search, opening
an invalid path would show errors such as "vapoursynth not found" when
VapourSynth wasn't installed, even if VapourSynth wasn't selected as the
default video provider.
This default script will be executed to load any file whose file name
extension is not .py or .vpy .
The gui code for setting the default script is still a bit wonky as it
doesn't fit the rest of the preferences pages nicely, but it works for
now.
odrling