You can make comments on their Facebook site: http://www.facebook.com/pages/Medievalistsnet/5740303430
They got some harsh replies allready but are defending their decision to post the vid and the "authentic pieces" shown. I checked the website of the designer and there I didn't find anything medieval - all fantasy. Not to speak of historic cutting and sewing techniques... Don't get me wrong, fantasy is ok. But if you call it "authentic" it has to be as close as possible to actual finds or at least to historic illustrations.
Does this mean I can't dress all my men in black leather, head to toe (just like the TV Middle Ages!) in my novel. I now have to go back and change a zillion references! (Before you refuse to speak to me ever again, I was lying. Shoes and purses and messenger bags appear, but no really cool armless vests or trousers or other garments. It's very sad.)