Oxford Internet institute
http://webcast.oii.ox.ac.uk/?view=Default
This site has a huge range of webcasts from the University of Oxford. There are a huge range of webcasts that are available here. These cases can be downloaded as MP4 format files.
The topics are interesting and varied often with social contexts. These are more suited to the senior students.
The site is searchable by category and date.
Interestingly the cybersafety series is jointly created with Netsafe and the University of Auckland.
