Shooting the videos would cost $250,000? Maybe in 1984. Shooting training videos is incredibly easy, given the cheap software that exists today. How do you think Cardrunners, Deuces Cracked, and many others made such a profit? They put the burden of production on the trainers, who basically used the software they were given (or instructed to obtain) and slapped the videos up on the site. Sure, you can spend unnecessary money on frills such as special-effects and graphics, but why? People watch poker training videos for content, not production value. They want to see how great players think while playing their hands.
To say "You can just do a chargeback" isn't a fair answer. A chargeback is a last resort for when the merchant turned out to be a crook. It also can reflect badly upon the purchaser if too many chargebacks occur in a short period of time, so it is wise to save them for when really necessary.
You also said that you don't have access to the database of e-mails. Are you saying that Helm would refuse to give this to you, if you told him that you were going to refund all of the aggrieved parties out of your own pocket? I find that hard to believe. If so, then you should really make a public stink about this and prove that Helm is the actual bad guy here.
I am afraid that there are still too many unanswered questions here, and there seems to be a lot of double-talk involving something simple -- getting a list of e-mails of affected parties, and refunding them $15 each.
Again, Helm may not have started off intending to scam people, but running off into the sunset with people's "pre-launch" money after the site fails definitely qualifies as a scam.
Too often people take the attitude of, "Businesses fail every day" as an excuse as to why they don't pay their creditors. That's garbage. You should only spend the money you have when hiring people for services that your business needs. You should not be spending expected future profits, and screw whoever you hired if your business fails to make what you hoped. Otherwise, you're basically freerolling other people. If your business works out, you pay the help you hired. If not, you screw everyone. Very unethical. Helm (and you, by extension) should have made sure you had the capital to pay for all start-up costs immediately, and if you didn't, the people you hired should have known they were only getting paid if the business succeeded.
I can tell you that, if I were in your shoes, clearing my name would be well worth the $3500, even if the loss was someone else's fault.
You have told me both here and in private e-mail that this thread is "defamatory". I disagree. I believe it is a fair discussion of the circumstances of a failed business and the people who were victimized by it.