Click on the 资源中心 section of the navigation bar, then choose your area, e.g. 经济学类, then click either 视频 in the search box, or 教学录像 on the left hand options menu. Then you'll get a whole bunch of lectures such as 微观经济学, 国际金融市场创新 etc.

Hmmm, although all the videos I just checked then only seem to go for 30 secs.