Thanks for the youtube video. I believe the problem you are describing is this: Your model moves its arms and legs in a walk cycle, but the model does not move from the center of the grid -- there is no X or Y motion while the animation is run.
If my understanding is right, this is easy to fix: Your walk cycle animation does not include any "forward" motion in the animation. You can add this separate from the walk cycle and make them separately controlled. You could make the legs move faster (by adjusting their scale as an Action Strip, if that is how you have the walk cycle saved) and also adjust the f curve that controls forward motion (if that is what you used).... Again, there are a couple of ways to combine multiple actions...
But I think the essence of your problem is that the walk cycle itself does not include moving the model forward... (I did not download your model, as I do not recognize the download site.)
Shout if I can assist or if I misunderstood.