How to download youtube video and convert it to mpeg

Sometime we need to watch some videos we found on youtube, which is usually in flash video file format (.flv). We don't have to be connected to internet all the time any time we want to watch it again. Once we have donwloaded the video from youtube, save it in our hard drive, then just play with the software we already installed on our computer.
Below the steps we need to follow in order to do that:
1. I assume you have Firefox internet browser installed on your computer (if you use other browser, you need to figure out the similar way).
2. Install DownloadHelper extension for the Firefox.
3. Go to www. youtube.com and open the video you want to watch.
4. Download the *.flv file by clicking Tools>DownloadHelper>(filename)
5. Change file name extention to flv.
6. Run VLC media player (a free multi platform video player software). If you don't have it on your computer, you need to download and then install it.
5. Open your video fiel (*.flv) you download from youtube and then play it.
6. Enjoy you vide0.

If you need to convert your flv video files into other formats such mpg so you can play it on your DVD player, you need to use for example Riva Encoder to do that job for you. If you use Riva Encoder to convert from flv format into mpeg format, don't close the program when nothing seems to happen during conversion. In my experience, during conversion, Riva does not show anything indicating the progress of conversion, even the window is greyed out. Just wait and it will be back to normal appearance when it's done. Good luck.
Hopefully this will hel you.