I've seen it the first time on youtube about 5 years ago, mostly in independant shops. Main dealers usually intend to sell new cars or new gearboxes, so they actually don't have the incentive that your AT lasts forever. They are quite common now in Germany or in Austria (first video was from there) but not at the official dealers. My independant mechanic (one man shop/w) who always has the newest machines/toys in his shop also has one.

It surely makes sense every 40k or 60k miles to do a complete 'blood transfusion' with new filters (good comparison, Clive ), esp. as the AT in our old Audi went kaboom after 120k miles and Audi says it's a lifetime filling. Ok, yes, the new transmission DOES come with new oil, thanks Audi. Never ever...

Not sure if it works with the filler tube but a pro will know the answer.