Comment by pixelHD

Happens to me too. I use a display link'd dell dock from work, with 3 monitors. Every few times i plug it in, the wall papers revert, and the wallpapervideoextension process starts soaking up ram and cpu cycles (I dont use video wallpapers at all, just static images from my folder as wallpapers everywhere). I've made it a habit to check the activity manager everyday after I plug in the mac, and kill that process if its taking up too much resources.