When they go "Early Access" a.k.a. Beta around October, the NDA will be lifted, videos will show up, and you can make your purchase decision. What you miss out on is the ability to get Elite Founder status, which gives you all DLC and expansions at a long term significant discount. The Founders' Vault is interesting, but mainly for lore and game design nerds so if that's not you there's not much you are missing. You'll have to base your Founder purchase decision on the small amount of info you currently have available to you.