Byzantium is a truly interesting package, which allows us to record what happens on our desktop and save it as . Gif by just running a line in the console. If you click on the image to see it full size you will see what I am talking about 
byzanz-record -d 10 -x 0 -y 0 -w 1024 -h 768 ejemplo.GIF
To understand this a bit, we explain what each parameter means:
-d = Weather (in seconds) to record. In the example it is 10 seconds.
-x -y = The coordinates to record. Putting 0 will record the entire desktop.
-wy -h = Width and height of the GIF, it must be according to the resolution of your screen.
Byzantium also allows you to save the recording result in .OGG / .OGV including audio in addition. An example of the command to use would be this:
byzanz-record -a -w 640 -h 400 -x 320 -y 200 -d 10 ejemplo.ogg
Part of the article I took from the blog of Humans.