It's SOP throughout most of the industry to script demo builds. The vast majority of pre-release dev walkthroughs and the like are scripted so that they can demonstrate the features they want to in what they perceive as the ideal circumstances and avoid giving away anything deemed spoilery or risk having the whole thing derailed by bugs/incomplete features. There's nothing inherently nefarious about it as a practice.
As for the 'mostly working game in 2014', there are at least three realistic reasons for it not being subsequently produced.
1. This was prior to the (admittedly overly ambitious) stretch goals being met, which necessitated major rewrites. I wouldn't be particularly surprised if it was a case of going back to the drawing board for a
lot of underlying systems.
2. We know the dev is, to put it gently, disorganised. I'm not prepared to assume he adhered to strict version control throughout the entire period of development. It's fully possible that said files simply no longer exist in that form. Hell,
even professional AAA studios have lost access to their source code in the past, and I'm talking entire released games here rather than merely a several years old build.
3. He simply doesn't want people to see a WIP. As much as this being the sole reason would annoy me, I could still empathise with this. I shudder at the mere thought of someone poring over and critiquing my unfinished work.
I'm not saying it's definitely all legit. Mainly because I'm not quite big headed enough to present my assumptions as indisputable fact (cough cough). I'm saying there's no particularly definitive evidence either way and freaking out whenever someone casts doubt on your Proclamation From On High does nothing but make you (general you, there's more than one person doing this) look like a bit of a prat.
I will say that if it is a scam (and it might be) then Josh needs to get an award for being the world's dumbest scammer. Far less effort could have been put into maintaining a thin veneer of legitimacy, and popping up every now and again with a video would be more than a little counterproductive. If I'd scammed people out of some cash then I'd do my best to
avoid reminding them of this on a semi-regular basis.