This is an important part of the process. The majority of hype nowadays is generated by folks streaming games right before they are released. This is just the reality of the situation.
You shouldn't view streamers in any different light than reviewers. They serve much of the same function - informing users of the game (and giving them a glimpse before they purchase) and generating hype for the release. They also work off of the same principles. In the same way that reviewers won't publish reviews on games if they don't get exclusive access, streamers won't stream new games if they don't have exclusive access. Obviously that isn't universal, but it is a good rule to follow.
This isn't to denigrate the backers or what they mean to this project. We love you guys and what you do for this project more than you can know. But, this is the game that has to be played for us to be as successful as we can be.
I agree that streamers/youtubers are a BIG part of the process, but unless Paradox are giving you guys some kind of financial bonus on pre-order sales there's no reason why they should get to play the game 4 days before the backers. The success of a game isn't defined in the first few days prior to release. Look a Larian studios with Divinity: Original Sin. The big name streamers and youtubers will still do what they do even if it's on the 26th. And why would the review embargo be different from the streamers? Doesn't make any sense to me, man.
Also I have a youtube channel. 1500 subs. Can I get a press release version? I can confirm some sales I sent your way already with my BB videos. You can also Youtube search Divinity Original Sin and you'll see my work in the number 4 slot. You can also youtube search Pillars of Eternity and find me in the 8 slot with my latest BB video. Kthx in advance brospice.