Thanks Hans for your input. Much appreciated.
I'm absolutely not happy with my filming. So it's good to hear what to do better.
Next time I want to try anyway a new Recording Tool on my iMac. Don't know which one yet. Any recommendations?
And I agree, the play-along is too soft. Didn't think straight here.

But ...you are wrong on two things:
first: I'm playing a Tenor Sax, not an Alto cool
second: you can easily play solos also on Baritonsax. Listen to some tunes of for example Gerry Mulligan.

Greetings from Switzerland
kindofswiss