As I'm feeling spiteful, I want to add that you can easily block the ads with firefox + ublock origin on Windows. So it's hard to believe it's some technical thing related to securing the ad playback.

I haven't tried spoofing the user agent yet.

But even if it did the trick, I just don't get the reason behind blocking other OSes.

Now that I think of it, they probably just spout out the user agent my browser sent in the error message.

I would be fine with watching some ad supported movies if they let me...