In the video you'll see that I started with a Generic Model family template, open Family Types and type a value into the Model parameter in the Identity Data group. Then I add another and another and even create my own parameter, then rename it... all the while closing and then reopening the dialog. As soon as it opens the position of the parameter shifts around. Seems to be moving parameters that have data to the top of the pile so that empty parameters are below the rest.
I think it's pretty subtle?!?