As far as I can tell there are lots of tiny fragments each about 1-2 seconds long rather than one video file.
It's actually not just a video, but a specially designed player that shows the lecture video and the slides in sync, along with a bunch of bookmarks so you can jump to specific slides.
Try it in Chrome. At least on the Mac, there's a dedicated but cut-down version, which does not require SilverLight. It's based on FlowPlayer and it also seems to work with Flash disabled.
It's actually not just a video, but a specially designed player that shows the lecture video and the slides in sync, along with a bunch of bookmarks so you can jump to specific slides.
Try it in Chrome. At least on the Mac, there's a dedicated but cut-down version, which does not require SilverLight. It's based on FlowPlayer and it also seems to work with Flash disabled.