Using keyboard movements for walk cycles

As I was looking up tutorials, I discovered another way to use keyboard movement for walk cycles. This is the tutorial:

http://tv.adobe.com/watch/create-like-crazy-with-adobe-edge/episode-10-controllable-characters-in-an-interactive-environment/

Referring to this, I managed to make the character walk while the background is moving, but one problem is that at one point the character walks out of frame.

Here is how it looks:

http://www.youtube.com/watch?v=6ULp3pprGRg