The manual is worth a read. This is a software (as gcc) in which the "man" page or the information displayed with "--help" is not near the bunch of things there are described in the complete documentation.
Could you post a link, please? Searching for those terms leads to a '96 book and some different blog posts, but I am not sure if the ones you are referring to. Thanks!
Well, both the article and the video say that there is more than one factor for reaching stability, not only momentum.
I think that this is the current status, knowing that the bike does not fall by the simultaneous combination of several factors. When analyzing the problem mathematically, it can be found that there are additional stability factors that do not even have direct physical meaning.