Hal Galper
There are portions of various Hal Galper masterclasses on Youtube in which he discusses various aspects of jazz improvisation. I found them very instructive, and thought you might, too. Don’t be misled by the titles, his lessons are equally valuable and applicable to all instruments. The last video listed is not a masterclass but captures Hal playing a really hip solo on ATTYA.
Piano Lesson–Minimizing Emotion