Enable remote control via local network and write down the network settings:
From the XBMC main menu enter: System->Network->Services and enable:
"Allow control of XBMC via HTTP".
Write down the port number.
Go back to the main menu and enter System Info submenu (right arrow on
System, then choose System Info).
In the System Info Summary check the "IP address" and write it down.
Configure the extension:
Enter the extension's preferences page. In Opera press Ctrl-Shift-E, find
the TeleTube extension and click the configuration icon on the far right
and choose "Preferences".
In the Playback Device from the Device Type drop-down choose "Boxee / XBMC".
In the Device Address field type the IP address that you got in point 2.5 above.
In the Device Port field type the port number that you got in point 2.3 above.
Click Test Connection and if everything is OK click Save at the bottom of
the options page.
Test it: Go to YouTube, find a video and click the button that is placed over the video.