Zentation is a very useful service that allows you to easily synchronise your video clips with your Powerpoint presentations.

You first have to upload your video to Google - then upload your Powerpoint presentation - and then sync the two together using the 'ZenSync' tool.

The end result can be viewed from their website - or embedded directly into your own website/blog etc.

The combination of video and Powerpoint can be very useful in education. Let me know if you create and presentations!