I believe in the video walkthrough, the guy said that it is possible to tell the next steps just from the numbers. However, I can think of several examples of why I don't think this can be so.
Take the image above, for example. The solutions of 2S or 2D are equally valid. However, a big difference is going to be made by which we choose; we can either insert the 'C' and Substitute the 'A' and then delete the 'T', or we can substitute through.
However, which one we choose makes a huge difference. Because the full words may be "cat" and "ate" the PRIOR numbers alone, it seems cannot be used to solve this ambiguity, unless there is some rule I'm missing. Therefore - though the video does not seem to suggest it - it seems to be a need to keep track of the paths you have created, and a need to choose this path based on future entries.
Is this true, or is there something else I'm missing?