I am trying to make previews of mp4 videos work on pressing spacebar (like with images). After surfing the net I tried several solutions, like adding gst_all_1.gstreamer, gst_all_1.gst-plugins-bad, gst_all_1.gst-plugins-ugly, gst_all_1.gst-libav, ffmpegthumbnailer to my configuration.nix, but to no avail.
anyone has already found a working solution?
It is mostly just unstable in the sense that new versions of software will appear, breakage will occasionally appear but it tends to not be a problem thanks to rollback (see e.g. this discussion). Maybe using the same terminology as LibreOffice does (unstable → fresh, stable → stale still) would be more fitting.
The main difference is that with stable you get a set of release notes every 6 months that tell you all the things that may break your system if you update to the next version. Within those 6 months, upstream tries its hardest not to break anything.
This means you only have to fix things once every 6 months, instead of potentially every time you update. That’s the idea behind all stable release distros. It’s less risky with NixOS, since you can always roll back anyway, but you still might not want to be forced to fix something if there’s a critical security-related update.
Which you end up preferring is personal taste. Perhaps it’s less important for personal computers, since you don’t need to meet potential regulatory or contractual requirements… But personally I like always being able to update.
Unstable doesn’t make the guarantees required for this. But indeed, it usually takes a little longer for stable to get updates or fixes (looks like @jtojnar backported the fix after reading this), I find that it’s rare for this to be more than a week or so, though, and for anything critical it’s usually much less.
And if you can spot a fix yourself, backporting them isn’t hard.