@lynne@pars.ee I think the common naïve assumption would be that if you want to cut 30s, and you have keyframes at 25 and 35, you should be able to cut and re-encode 25-30, then prepend that onto a video from 35 on.
Not sure if it's possible to concatenate videos like that without re-encoding the whole thing like it is with mp3s, though.