I don't understand multicast
 

I can see video streams with my browser at home.
How can I see video stream with my browser if my home router is not multicast capable?
Is there any home wireless routers that are multicast capable?

I think you may have it just a little bit backwards -- multicast is from a provider to you, not the other way around.

Take a look at this Wikipedia article, it may shed some light (and it doesn't make a lot of sense reproducing it here, eh?): http://en.wikipedia.org/wiki/Multicast.

Hope this helps some.

Thank you tronayne, I did get it quite backwards, and wikipedia did clarify things. But still there is a thing I do not understand. As a programmer, how do I write code in C that will join a multicast group, using POSIX sockets? Do I have to send a request to the IP of the multicast server? How do I read the multicast info? Is the destination address of the packets I receive is my IP or a multicast IP?

Well, essentially, you don't. A sub-article to the above one, IP Multicast http://en.wikipedia.org/wiki/IP_multicast, discusses the how's and why's. Kind of bear in mind that you're more or less just a passive receiver of multicast data; multicasting is a method of efficient transmission, not reception (as pretty much explained in this article).

So, give this article a good read and take a look at the sub- sub-article Internet Group Management Protocol http://en.wikipedia.org/wiki/Interne...ement_Protocol referenced in the IP Multicast article above. That may be helpful.

Keep in mind that this is pretty complicated stuff and it's not all that easy to get your arms around -- it's fiddling with IPv4 and IPv6, routers, protocols and a whole specialized world that most of us never see. The Wikipedia article in the first post is a good place start, being sure to follow the links to sub articles.

Hope this helps some.