Family member with brand new MacBook can't Video Chat??

So one of my family members just bought a brand new Macbook. Also, one of his sons also bought a brand new Macbook. I have had mine since July and when my cousin turned his on, we instantly were able to Video Chat. However, my uncle who just bought his is having problems connecting with us.

We can even talk in regular iChat instant messaging but not in Video Chats. I'll request to him and he'll accept it but then it'll just say there's a connection error. Same goes if he sends to me and I accept.

What could enable us to talk over the IM in iChat but not Video Chat, where my cousin's computer he just opened it up and out of the box we were able to chat.

Also keep in mind my uncle is in Hawaii at his house, and my cousin is here in New York, so they were on different internet connections.

ANY HELP WOULD BE MUCH APPRECIATED!

But see he went to the Apple Store, and he was able to do it through his .mac account that he set up when buying the laptop. But all of us are using AIM accounts - so we set him up with an AIM account to use so he could chat with us and there it doesn't work. He says he sees his picture on the screen waiting for my reply but even if one of us accepts it doesn't go through.

I've been reading a lot and lots of people say it's either firewall related or not all the ports for iChat Video are enabled through the router.