I believe you can, but curious, why would you need to? What's important is cutting the signal to whatever Video monitors you are using. I often have video running even when not actively showing video, just to have some visuals on the screen to watch on slow nights. Most of my newer library is video so I'm playing them anyways, whether they are output to the club or not.

Go to the Setup tab in Searto and uncheck Video Plugin. This will shut down Video without affecting audio.

why not just drag the fader for video down... Simple.