I don't consider myself to be an animal lover. In fact, I really don't like animals very much, but this video shocked me.
I was a bit suspicious of the pictures that showed images of how the breeds changed over the years, so I decided to try and find a picture of a pug. Lo and behold, it was easy to find a much healthier looking pug on Wikipedia.
This painting was dated 1745. I would imagine that this pug doesn't have anywhere near the breathing problems that today's pugs do.
My thoughts on in-breeding:
I'd like to point out that in-breeding in and of itself is not a bad thing. Sometimes it frustrates me that people seem to think so. It's when dogs with genetic problems are continued to be breed with one another that problems arise. Case in point the Rhodesian Ridgeback, German Shepherd, Cavalier King Charles Spaniel, Pug, etc.
This is not to say that I advocate in-breeding. Of course, even the healthiest of breeds are going to have some genetic problems, whether they are immediately noticeable or not. I don't advocate in-breeding, but I would just like to point out the misconception that in-breeding automatically causes problems to appear. My high school biology teacher would erroneously word it this way and I see many other people that do this as well.