Hey Jutta, it is a very good question and you raise a lot of points.

The awareness of the aperture corners and the inward – horizontal movement is to avoid clamping down the chops in the middle. In the low register, I simply want you to recognise the extra firming of the aperture corners at the rim of the mouthpiece.

Have you got the “sympatheitcal oscillation” happening on the leadpipe. You will really feel a looseness in the lips and a slight grab at the aperture corners. I don’t want to think further outside the rim, that is all taken care of with the activity of the corners.

As far as ‘smiling’ goes, Watch 3:17, the appearance is a smile but the grip is inwards.

The course is comprehensive and if you copy the instruction, you will get the results.

In looking for the finger demo, I rewatched the Mouthpiece Revisited and the Leadpipe/SHAPE revisited. There are so many answers in those two videos alone.

Hope that helps.
Cheers,
Greg