By default, Jabber will automatically start your video when you place a call through Jabber.  To change this setting, please follow the steps below:

1. Open Jabber on your computer
2. Click on the gear icon in the top right 
3. Select File > Options​​​​​​​
   1. 
4. Select the Calls tab and select Never start calls with video
   1. Make sure to click "Apply" to apply the setting you just changed

Note:

If you want to start a video during a call press the Start my video button in the top right of the call window.