SkunkyArt | Ambassad0r — Grumpycorn (+Timelapse) [Vectorized]

Use SimpleScreenRecorder/X11 to capture video (my desktop shell hides currently running applications, so I can feel safe in recording the whole screen)

Load the video into Blender's sequence editor. Optionally add audio here.

Using a speed control modifier, speed the clip up so that it ends with the audio or at least a sensible ending point.

Render an AVI.

Use ffmpeg to re-encode the AVI and add MP4 compression levels so as to reduce the filesize. (You might be able to do this with avconv too, idk.)