This could have been more precise. The example at the start was great, but there's no example of the lecturer's technique outside of the link to the actual lecture
After reading that, I think structured proofs should be written with an outliner [0] interface, where you can actually expand and collapse the hierarchy. Lamport also knows this. He repeatedly mentions it as "hypertext". However, he seems to be locked into LaTeX [1] and pdf generation.
http://research.microsoft.com/en-us/um/people/lamport/pubs/p...