"Anonymous. Originally you argued that the front foot does not get ahead of the body. that it got to the point of imbabalance and falls onto the next step, or is caught."
More or less, yes. The front foot at least shouldn't be getting ahead of hte body this early in the step... that is what is wrong with the picture. What is right is that the body has clearly been projected into a position of imbalance, well forward of the standing foot.
"To me imbalance means to get to a point where the foot has to move to catch the body."
If your center of mass is not over or between standing feet, you are off balance, end of story. Since the picture shows the entire body well ahead of the only standing foot, this is obviously an example of imbalance. (and quite severly so, with all that weight of the moving foot forward far too early)
"If you go to the Learning Centre. click on Forward Walks you will find a moving computer image of a Forward Walk."
Yes, you will see a video created by someone who now himself considers it not quite right.