Speed does matter and anyone watching the video can plainly see that the cyclists are keeping up a good clip. (I'd say around 20 mph, which is what I try to do in similar situations)
Nothing in the video says to me that all cyclists should want to ride as shown. Instead, it demonstrates nicely that doing so properly is relatively safe. While some will say "not for me" others will be inspired to venture into traffic they previously feared. Either response is fine.