Hi there
I'm presuming you're using Dolphin 7.3.3 and you have the Chat module installed already.
If not install the chat module from the Modules/Add Manage Modules area in your Dolphin Admin Panel
To get the video chat up and running you need to install the Ray Media Server (RMS) media server. You can do a search for info and the download link in the forums.
Once you have installed the RMS start the server then go to the Flash Apps in the Modules section of your Dolphin Admin panel.
In the Flash Apps Admin Panel that has opened click on the settings option in the top left.
In the Ray Base Settings panel that opens check the Use RMS check box and enter the IP where you have set up your RMS.
Click the Save button and providing your RMS is running and you don't get a "can't connect" message things are set to go.
After you have done that you should be able to go to your chat page and you'll see that the video cams option that you didn't have before is available in the chat now.
Hope this has helped.