另一種方法

How to insert Google video into PowerPoint？A detailed guide in the link below:
http://www.deadgekko.co.uk/images/pptgoogle.pdf

This method requires you to install an add-in for powerpoint.

You can find the add-in here: pretty handy
http://skp.mvps.org/liveweb.htm

By using this method, you don't need to download the physical video to your pc.

BTW, Since youtube was acquired by google, any content in google video actually is provided by youtube. So you can use the way as I mentioned in the first post above:)