I have a PHP/AJAX/MYSQL chat application. I want to add video chatting to my application. How can I create live video streaming to be used for live video conferences/chatting in a PHP application. What are the key-terms I need to know if I wanted to build such a system? Is it a good idea in the first place to use PHP? Is there something I'm not thinking about? What other languages can I use, perhaps in conjunction with PHP?
I am not saying that you have to abandon PHP, but you need different technologies here.
Let's start off simple (without Akamai :-)) and think about the implications here. Video, chat, etc. - it's all client-side in the beginning. The user has a webcam, you want to grab the signal somehow and send it to the server. There is no PHP so far.
I know that Flash supports this though (check this tutorial on webcams and flash) so you could use Flash to transport the content to the server. I think if you'll stay with Flash, then Flex (flex and webcam tutorial) is probably a good idea to look into.
So those are just the basics, maybe it gives you an idea of where you need to research because obviously this won't give you a full video chat inside your app yet. For starters, you will need some sort of way to record the streams and re-publish them so others see other people from the chat, etc..
I'm also not sure how much traffic and bandwidth this is gonna consume though and generally, you will need way more than a Stackoverflow question to solve this issue. Best would be to do a full spec of your app and then hire some people to help you build it.