Can someone confirm this? I mean the grass and small trees are ok but the firtrees are all frozen for me! And I saw an Xbox gameplay video where they swayed...

Maybe it's not windy..

try playing some hula music

I just checked for you and, yep. They don't sway. Have a tree that is completely static and a large bush next to it that is moving in the wind.

Now... Are trees even supposed to sway in the wind or?

Yeah i thought 'bout it but the moment in the video is right after you escape the first dragon(thats the moment when I noticed the bug) so the weather must be the same...

Thanks...
Yep they do, in the Xbox version of the game at least

I had this problem, only the tall pinetrees would not sway but the rest of the foliage was fine.. Changing the settings from Ultra to High seemed to fix it. I don't think my computer was fast enough for Ultra.