This bookmarklet is very dependent on the structure of video.ethz.ch's HTML. Slight changes can and will break it.
Select, then drag & drop the following to your bookmarks (or create a new bookmark with the following URL):
javascript:var%20win%20%3D%20window.open%28document.querySelector%28%27li.video%20a%27%29.href%2C%20%27_blank%27%29%3B