thank you so much for posting this. i'll have time to watch more this afternoon - but am watching the part about the mozart fantasie right now. i agree totally with what is said about tremolos. i've found, too that sitting up straight helps the arms move freely. in fact, to the extent of what you are doing with the neck. if you lean too much forward with the head - it somehow inhibits the arms (probably stemming from the back) from being completely relaxed as they could be.
surprisingly, when i think about posture (head above spine) - immediately i feel a wider range of motion. and, of course - as mentioned the upper arms being relaxed and not pinned to the sides of the body.
i'll think of some questions while milling around the house today. i'm sure that there will be many. this sort of thing is very very helpful. basically, i think you covered the hardest question about the fantasie (the piu allegro) - because if you play this part as though it's individual notes and not tremolos - you're shooting yourself in the foot. a little bit of hand quiver surely does one good. although, i do have one question - do you play this part as though you are paring two instead of four notes? because otherwise you have this close grouping of the pinky to the fourth finger on the last two thirty-second notes in some places. this is like going from tremolo to trill. kinda like you have to be closer to the keys on the trill-like spots? or am i wrong? perhaps what is in question is where one decides to put the focus. mid-point? with wrist there? or towards the pinky and use the 'zip' technique to get from the lower note to the comfortable position where there are more higher notes (3 to 1 - so to speak).
a lot of people think they have to connect each note and therefore never give themselves any real flexibility to just move where it's easier to play. and, their hands get stiff from being outstretched to the max.
i guess what i am saying is that i totally agree with what you all are saying - and yet also would like to add just a little bit of the horizontal movement of the arm with the hand quickly at the beginning of each tremolo - adding to the ease of playing this. perhaps you already covered this by explaining the rocking movement that the forearm does.
Topic: First seminar video up