The previous screencast may have tried to use too much technology to enable user-centric simple web payments.
After looking around some, it occurred to me that the rel-payment microformat is not sweeping the world wide web. Using the Internet Archives, I found a blog post from July 2005 that announced support for rel-payment on blip.tv. I’m guessing not many people used this before it was abandoned.
An alternative to rel-payment is to simply use a convention. For instance, the path /blog is a convention to quickly find the blog for a site. On Twitter, this would normally represent the person with the Twitter handle “blog” but Twitter follows the convention and redirects to blog.twitter.com.
Similarly, url paths that began with /transacts (or something similar) would be a lot more user friendly than using a microformat. Now we can use a simpler bookmarklet and achieve the same flexibility as rel-payment. A convention like this would be compatible with OpenTransact.