When I use my 3D printer, I'm recording the printing process. A Raspberry Pi, with a Camera module, takes a picture every second. These pictures are saved and later imported to Blender.
First I need to switch to the Video Editor part of Blender:
Then the images needs to be imported.
Then I use the command:
ffmpeg -start_number 1 -i %04d.png -vcodec libx264 outputfile.mp4
If the render is has a framerate of 60 FPS then I add -r "60"
This combines all the .PNG files into one .MP4 file.