It is possible to download multimedia items which can be dislayed at youtube like web sites. Firstly if you don't have Mozilla Firefox, please get the latest version of Firefox from here. And after the installation of Firefox, you must get an extension to download ".flv" files of watching items. I am using Video DownloadHelper currently. But there are more add-ons to use for that aim. Let's try one of the video that I published before about Multi Touch Screens (22.6MB)
After all installation you can see an icon at right of the navigation toolbar when you are at a video given page icon will be activated so click at that icon and see the downloadable ".flv" items.
Yeah! You get the file. Now you can get Adobe Media Player prerelease version and watch your local videos. Only a drag&drop movement or double click :)
Adobe media player has a great interface and easy to use. You can use for online media player or flv player. Have a nice view!
As a summary of this tutorial get Firefox and Adobe Media Player! :)