You can view the lectures online, or download them for offline viewing. You can also view them on a computer or on an iPod. On the computer, you'll need flash player to view the videos. Flashplayer plugin or ActiveX control needs to be installed to view the lectures in the browser. You can also use a standalone flash player or VLC media player to view the downloaded lectures. Older lectures are in .swf or .flv format. More recent ones are in .mp4 format and are also available in .m4v(iPod) format(320240 video, AAC audio). You can replace the .html file with .flv or .mp4 as appropriate to download the lecture. For .swf files, right click and do save link as. If using a standalone player, open the media files, or the *_controller.swf if you have downloaded the whole directory.