So, "fusion" then... Fusion is of course a very broad genre, so we will just focus on the kind of modern fusion that leans heavily towards quartal harmony and such. In the first part, with the progression borrowed from the Vibrato tutorial, we were very much guided and "lead" by the voicings. We were, as I mentioned, "expecting" to hear the F and G major after the A minor. This will of course guide us when we improvise, and to then start playing "out" would not sound all that good. Not that "good" or "bad" is absolutes in music, what I mean is that you should take the stand point of the listener in this tutorial, rather than the player. This is also why i stress the singing so much!
However, when using other kinds of voicings, having all three voicings being thirdless, it opens up some new vistas for improvisation! In traditional fusion and jazz, we're expected to follow the chords with appropriate scales and note choices, or it won't sound "jazz". In this case I want you to let that go a bit, and rather experiment with trying to suggest both major and minor through your playing.
Listen through the video part, and once you've done head over to the next part, listen through my short improvisation, and then just go to the backing and go crazy yourself!