As I was making an Animation I found my self to oftenly press AltA to start and stop the green slider, and then when I stopped it I had to get it with my mouse and move it back to the beginning of the Timeline to see the Animation again.
I know that you can cancel the animation, and take the slider to the beginning when its playing by pressing Esc key but I can't get used to that.
You can see what I mean in the video below on Minute 5:40 - 5:44