Ok there are several possibilities to download a video from youTube, Google video, or any video sharing site. Here are 2 of them:

  1. Using Mozilla Firefox’s cache. First find out where the browser stores the cache files by typing “about:cache” in a new Firefox tab. Then open the video that you want to save to your computer in a new tab. When the video starts Firefox begins writting a cache file to the previous found folder. After the video is completly loaded you should just copy the file from the cache folder (beware at the creation timestamp!), give it a “.flv” extension and you are ready to go.
    This option has a big fault, and it seems that the Mozilla developpers wont fix it. The browser wouldnt create cache files larger than ~67 Mb and the user can’t change that limit. The size of the whole cache folder can easily be changed to any value by going to Firefox’s Tools>Options>Advanced menu. (the default value is 50 Mb)
  2. Using Download Helper - a Mozilla Firefox Add-on that enables you to get virtualy any video/picture from almost any site. A minor disadvantage of this add-on is that it only lets you download one file at a time, butt I still preffer this way of getting stuff from video sites.

For playing .flv files I recommand Real’s Real Player