Nice to see you're still in circulation Edward, and furthering the cause of improvisation. It seems to me that the things which impart life to improvisation are primarily phrasing and rhythm; whether one uses few or many keys and chords doesn't matter in the end. Dare I say it, even the precise harmonies used are of far less importance than feeling the flow of phrase and rhythm. This little exercise held its interest through the internal accents and phrasing. For example, in the left hand passage around 0:30, you are playing a myriad of unequally accented notes. That's where the life resides. Without this, it would just be a static harmony, smooth arpeggio or the like.
In other words, the "how" of improvising is infinitely more important than the "what". And yet in discussions by the classical and jazz diehards and experts, in nearly every endeavour purporting to teach improvisation, all we get is the "what" - static, drier than dust harmony - in the form of barren combinatorics. As if all music can be reduced to learning combinations of notes, then stringing those combinations together in rhythmless sequences using hidebound rules, the reasons for which, if they ever existed, are lost in the mists of antiquity.
In my experience it is very hard for an older person to acquire this primitive improvisational flow. Or more correctly, I have never been able to impart it to an older beginner. In other words the deficiency could simply lie with me. I think it has something to do with getting rid of conditioned inhibition. They can memorise thousands of chords and have a tremendous analytic knowledge but still can't do anything dynamic.
I think you are on the right track though, and wish you luck.
Topic: Arctic Echoes ... A 1-Chord Piano Improvisation!