There are millions of videos on Youtube, specially bollywood rare oldies.
Here is a guide of how to download videos from Youtube.
1) Download Firefox from: http://www.mozilla.com/en-US/firefox/
2) Install Firefox browser.
3) Download/Install Firefox plugin/addon called "VideoDownloader" from: https://addons.mozilla.org/firefox/2390/
4) The addon automatically installs and embeds in Firefox.
5) Restart Firefox and you will see an icon on the bottom right corner of the browser window.
6) Browse youtube and select any video to watch, as the video is playing click the ICON on the bottom right corner of the browser window. It opens up a window and gives you an option of saving the file. Save the file on your hard drive.
7) The downloaded file will not have any extension, you just need to rename it as ".flv" (flash video file).
8) For watching the flash video file you need FLV Player, which you can download from here: http://www.download.com/FLV-Player/3000-2139_4-10467081.html
9) Thats it folks.
The same steps apply for Google Videos except for the file extension.
If anyone needs more clarification, do let me know.
You can convert the file to AVI or MPEG format using RIVA FLV Encoder: http://www.rivavx.com/?encoder
All the software mentioned in the guide are free.
Enjoy the videos!
PS: Browse my youtube videos: http://www.youtube.com/user/MdAzgarKhan
I uploaded like 500+ videos there.