It can still be professional players doing the demo/playing, but instead of external recording just use the inbuilt audio recorder (Without any external editing of the final sound) and post this online. (Most organ/keyboard manufactures/dealers in Europe (Bohm, Bemore etc.) do it like this so that a potential user can see what they can achieve with the instrument, (With practice) rather than something they can never achieve without the extra expense (And expertise) on external equipment) This is why I take online pro demos with a pinch of salt (And my comments relate to this) and don’t come to a final conclusion until I have tried it myself. (Too many people get sucked in with these pro demos (Or worse still buy because it has a particular badge on it) and then become disillusioned when they can’t achieve the same result)
Bill
First of all, the way some of these guys play is not very professional.
Second, they are clearly playing from home.
Third, you can read first-hand reviews posted on this and other forums. So far, the majority have said that the Genos sounds incredible, and better than the Tyros 5.
Lastly, like you said, trying one out in person is the way to go. It's the only way to quell naysayers.