There are several thereminists (including yers trooly) whose theremin/Talking Machine videos have been linked and featured on the Electro-Harmonix website. Manufacturers do not give stuff away unless you're a professional, concertizing, "star" player with high visibility. Back in the late 70's & 80's (when I was sellin' gold) I used to get free instruments from manufacturers all the time without asking for them or even wanting them.
YT superstar Jordan Rudess, who is a wonderful musician, has a Talking Machine video in which he actually discusses the device....I wonder if he got a freebie from the company. He uses the unit with a keyboard and although the sound is excellent, a keyboard cannot produce an emulation of a singer that is anywhere near as convincing as the theremin.
Rudess discovered, as did I, that the Talking Machine works best when a fairly harsh sound is fed into it. By far the best theremin I have to use with the TM is the Julius Goldberg RCA whose sound is almost unlistenable in its unmodified state.
My TM video has had far more hits than any other TM video linked on the Electro-Harmonix website and I sit by the phone for hours every day, waiting for that call telling me I'm going to get a freebie from the company......nothing........only silence....and tears.