That youtube video was not well done.
I'm a research statistician and if I was presented with that question for research, I would have been uncomfortable with the direction it took.
First, if you want to compare scenarios, you have to compare them in similar situations.
Model
2 variables(factors):Videogame Quality (2-3 levels) and, Demo Quality(3 levels) and one outcome, Increased sales (yes/no).
Simple enough.
The problem is then justifying conclusions based on factors that were not tested.
Game has a following? (yes/no): is it brand new, or are there expectations? "If they were interested in it, they would buy it anyway." is outside the scope of that model because they didn't test/include it as a factor.
Pre-order-able? (yes/no)
Game Type? (fighting/rpg/action/ect): Demos for RPG's are more involved than for fighting games, I'd posit.
Review_importance:does the consumer care about reviews?(yes/no): If I thought the demo was great, and the reviews say it sucks, who am I going to believe more, the review?
Review_score (1-10): Did the reviews actually have an impact on whether or not the game sold well? ---you have to ask both the score and the perception of the score to see if they are related to the outcome as they are not the same question.
I could go on, but that video was very disappointing. They likely combined several studies (meta analysis) but didn't likely combine the data (so not a meta analysis). One study could look at that info, but I'm not in the gaming industry, but I do hospital research instead.
There was a lot of talk about deceiving consumers. The whole "It's better for the company if consumers know less about the game and buy it anyway" mentality is mildly offensive. Knowingly selling a Bad game(how many developers would think of their own game as a Bad game? Insensitive...), as they put it, at full price is somewhat sketchy and falsifying a demo to upsell a bad game is heading towards 'false advertisement' territory...
Demos cost time and money, but marketing costs time and money. Video previews can face the same issues as demos. Good vid preview bad game? Great game bad video?
There is some logic to their demo complaint, but I question their, presented, research methods based on their sweeping conclusions. (yes, I understand that it was likely simplified). Although, I REALLY question the idea of someone "getting their fill" on a demo. What the heck? 30min of demo and," aaahhh, I'm satisfied; I won't buy the cow because that delicious
sip of milk was free"

>_>
On a personal note, DA2 demo got me to buy the game. I bought DA Awakening (thinking it was an O&A dual pack lol) and didn't like it(mage gameplay). I played DA2's Demo and NEEDED DA2, so I finished DA Awakening to import what little (awesome) story I could. I even convinced a few friends, that don't play the genre, to try DA2's demo. Some got the full game.
I'd love a demo, but I wouldn't demand one.