They get the audience stirred up (in a good way), and folks are rushing to the sales table to order Speaker X's package. But the package includes some component(s) that aren't yet fully developed. According to the presentation, things will be ready to go within just a couple weeks.
But, invariably, two weeks turns into a month. Then, a month turns into two months. You get the picture. Now people are getting antsy, and refund requests begin to pour in. It's not a pretty sight.
The solution — make sure you don't sell a product from the stage that isn't yet fully developed. If you absolutely must deliver a presentation where you're selling something that isn't completed, you had better at least make sure you have some component (either physical or digital) that can be delivered to the purchasers quickly to keep them happy until the remainder of the product is ready.
How does this apply to you if you're not a platform speaker? Pretty much the same way. If you're planning a specific launch date for your information product, work the dates backwards to determine when all the product development work needs to be completed.
If you think it's going to take a week to edit your audio or video, then you need to allot two to three weeks in your schedule. If you think it's going to take 10 days to finish up the writing of the manual, you had better plan on 20 or more.
We see it time and time again. Information marketers who don't plan properly who are scrambling at the last minute to get things to their fulfillment house to produce the product. This can mean delayed deliveries and rush charges for jobs, neither of which is a desirable thing.
Whether you speak from the stage or not, be sure your product is ready to deliver when you're ready to sell it. Communication with your customers is critical. If you manage their expectations proactively, then you can minimize the potential harm from not having a product ready to go. But the keyword here is "proactively." Better to just make sure it's done so you don't have to worry about it.
