"To answer Fred's comment, of course I am aware that I was really off key, but how is it possible to improve if you don't have any mean of having feedback from more experienced players?"
Then all I can say is that you have been really brave to present your performance, and I admire you greatly for this!
As I said on my opening line, I am not a thereminist or a "musician", so my comments dont have any kind of "merit" in this regard. I dont remember the details of everyone who posts here, so did not know about (or remember) your credentials. (and on-line credentials dont tend to impress or influence me much anyway)
My reply was split into two 'groups' - which comments might apply to you depended entirely on the honest answer to the question "Did you think your playing was acceptably in tune? ". As you have answered "of course I am aware that I was really off key" the only comments I made which may relate to you (remembering that I am utterly unqualified to give any comments at all ;-) were:
"I think you may have a hope of mastering the instrument through the kind of training Thierry suggests.. Apart from pitch, I hear nothing that couldn't be overcome with practice and training.. And if you can hear that you are off key, this can be corrected with practice and training."
And IMO your "how is it possible to improve if you don't have any mean of having feedback from more experienced players?" is an entirely valid and pertinent question / comment.. Posting your performance is (or should be) a great way to get feedback, but being public is open to misunderstanding or worse... Its going out onto a subjective "sea" and can be blown by some comment based as much on the commentator having had a good or bad day as on any musical merit.
There was much in your performance that I thought showed potential, and I am really glad that you could hear the pitch 'problems' because this means that realizing your potential can be achieved - It would be sad for someone to be as good as you but unable to get better because they were impaired (and this kind of impairment is real, and many people suffer it to some extent) , but such a person could still derive personal pleasure from the instrument, and it would be a shame IMO for such a person to lose this pleasure through discouragement - but likewise there is no point in directing someone to a path that is too narrow for them.
I wish that I had the potential you have! I can hear when I am off key, but unless I play incredibly slowly often dont have the ability to even get the first note in tune by the time I should be playing the third note! - its kind of got to the level where I change key when I need to jump an octave quickly, and continue the "tune" in a different key ;-) ... And that's playing a pitch-only... I cannot play anything if i'm messing about with the volume hand!
I was trying to be encouraging to you whatever you "were" LOL ;-) Not because I just wanted to be "nice" but perhaps because there was a lot about your performance that impressed me far more than the majority of you-tube or similar (IMO) theremin rubbish I hear. I cannot quantify why I felt this way, I just did... There are some reasonably renowned "thereminists" whose playing sets my skin crawling, and I would sooner listen to your performance than any of theirs even if their pitch is correct! ;-)
Please forgive my clumsiness if I caused offense..
Fred.