Wow! Seeing that video was a complete shock.
The only thing I can think of as to why they ran across the road is because Swedes are very reserved - so being pulled up by the police (which I assume happened) made this situation occur.
I have friends from Sweden that I met from university. Fredrik, Viktor, and Phillippe. They are very reserved, quiet and know exactly what they want to say and when/how to say it. Also, their very "people" cautious; an example of this is when I was at the bus stop back in Edinburgh, my friend Fredrik did not like standing near other people and kept at a distance. I wouldn't dare to assume all Swedes represent how Fredrik is, but Viktor is quite similar.
I think for the most part Swedes seem like this because it's part of their culture, everyone is different and has unique world views on how to see things.
I don't think for a moment though that people in the UK would dislike Swedes because of their nature. Nobody is the same and we should take appreciation in that diversity.
Personally, the Swedes I know are an excellent bunch!