Good Morning Hans,
Appreciate your reference to You Tube; using search engines available to me, I find well over 10 pages of You Tube videos regarding the use of Festool Parallel Guides. However, none of them address the combined use of your product with the Festool product. My inquiry was just for assisting me in justifying the expense of your tool, that's all. To date I've been quite happy with my Qwas Square and a single Parallel Guide attached to the opposite end of the rail. I do verify square with a variety of tools at my disposal: Qwas Dogs, Anderson Square, various Woodpecker precision squares. Thus, I guess I'm well equipped with what I already have.
I do wish you good success in this and all aspects of your business.