Disagree, big time.
Star Citizen, prime example. People put up thousands of videos on youtube when it was first in alpha and those of use who were the first to back it got access to Arena Commander before anyone else. Some of those videos went up into the millions of views, 2 of mine were 100k plus - and the crowdfunding dollars went from around 10 million at that time to the nearly 90 million. Much of that early explosion of interest was driven by videos those of us who had early access put out.
This is different in that generally anyone can get access by having a bbs account, but in terms of attracting new players, if you think that potential new customers are somehow unaware that they're looking at an alpha, not a finished product, and that somehow will be of more negative influence than the positives of seeing how things are generally shaping up...I don't know what to tell you. And for the record, those first Star Citizen videos had dozens if not hundreds of bugs - nobody cared, they just wanted to see more. Every Youtube gaming channel was abuzz in those early days with talk/walk throughs for those lucky enough to get first access.
This whole shtick of "secrecy" is ridiculous.
And besides, nobody was told they couldn't release videos, there was no NDAs signed, and I can't find a specific TOS readme in the Alpha docs anywhere stating "no videos", "no discussions", "no disclosures"...