First you need to install Mozilla Firefox (download firefox) after you done, run your Firefox and go to this link (unplug) Intall Unplug
What is unplug? UnPlug scans web pages and tells you where media players are getting their data from, and allows you to easily save the media file.
UnPlug works for lots of sites including youtube.com, video.google.com, metacafe.com, vimeo.com, veoh.com and lots, lots more.
UnPlug your Plug-Ins and view media however you want!
just click the unplug button and save the media.