I seem to recall that older Sonar versions could send video to a dedicated output port such as a DVI port etc. Is there still such a feature hidden somewhere, or what is the best way to achieve that considering I already run two monitors? I'd like a 3d monitor or dedicated TV for Video only in other words...

Maybe I'm mistaken but I think you can only drag the screen to the 2nd monitor...perhaps your thinking of Sony Vegas (or another NLE) where you select your preview monitor?

Yes, just drag the video output windows to the target screen, no setup required.

Obviously I do already drag the video to where I want it. I was hoping that there was a more dedicated solution for a third monitor / TV screen. I remember that Sonar used to have a dedicated firewire or similar output option in the video box if you right-clicked... that has not been there for a few versions now.

I remember that Sonar used to have a dedicated firewire or similar output option in the video box if you right-clicked.
 
Oh sorry, I didn't know that.

Via firewire http://www.soundonsound.com/sos/oct06/articles/sonartech_1006.htm
 
Not since X1 (when I got started).

That's the one... looking at the cost of good 3 or 4 output video cards, I wish they'd kept it!