<p>Is it necessary to pay $99 before I can watch the video to submit an iPhone application to the App Store, or it is available free of cost anywhere?</p>

I assume you are referring to the $99 fee to register as an iPhone developer?
Even if you can find a copy of the video, you would still have to pay the fee in order to get your application hosted on the App Store. Apple keeps a fairly tight handle on all of this stuff, so they require all developers to register if they want to sell software in the App Store. Apple will also have the final say on wether or not your software can be sold.
Bottom line: if you intend to sell software through the App Store, you will have to pay Apple the $99 fee.