The redhat and novell sites have decent quality video downloads - and the compiz/fusion site posts video previews of upcoming features.
http://reverendted.wordpress.com/200...uld-linux-fit/
... ri-res novell/mac spoofs linked from the blog page.
http://www.redhat.com/videos/
... redhat has a range of advertising and documentary style videos. Their lawyer explains about IP.
http://www-03.ibm.com/linux/linuxmov...imonials.shtml
... IBM have thrown themselves into the whole GNU/Linux and open-source thing.
If you want to make a demo vid of your own - you can.
http://news.softpedia.com/news/Scree...eo-42626.shtml
One of the things that proprietary vendors do better than free software folk is advertising - lets face it, they're the ones with the money. As more fortune 500 companies get involved, we should see better marketing.
Meanwhile - have a look at:
http://zgp.org/~dmarti/linuxmanship/
... boost your advocacy skills.
However - remember to chill out when telling people about gnu/linux. People don't have to adopt it ... so long as they know they have a choice. Remember, widespread adoption is not needed.