VideoLectures.net is an online database of videos of lectures from academic conferences worldwide. There is a very heavy bias towards computer science (1351 lectures) and – even more specifically – machine learning (625 lectures on this alone, over 1/3 of the total number of lectures). Only four presentations in the education category!
One of these is the Sugata Mitra lecture, below, hosted on GoogleVideo. Despite the failings, the site is a very useful resource – more so for some topics than others.