Holy hell! This is amazing! I just read both changelogs (QGIS and UE) and found them very interesting even though I'm not doing anything with either of them. I can imagine making such visual logs is much more time-consuming than just browsing through commit logs since last release and retyping commit messages in plain English, but the potential of such visual logs to actually get read and understood is much greater.

My question is - is there any tool that one could use to quickly capture a few seconds of a selected region of the screen as a video/GIF? Preferably one that would subsequently allow to throw away some frames from the beginning and ending. Such a tool would speed up the process of creating visual changelogs quite a bit.

Yes, LICEcap is good for this: http://www.cockos.com/licecap/

On Linux there is recordmydesktop and its gui frontend gtk-recordmydesktop. I don't have a lot of experience using it, but a few tests worked as expected.

The age of animated gif files is over. You want something that creates webm videos, like VLC or ActivePresenter.

Its not over until I can embed video in github markdown files. ;)

You can stop using github whenever you want to.