In the Kaltura Capture recorder ensure that the screen, camera and audio sources are selected. Blue icons will show it has been turned on. If the icons are grey, click on the icon to enable it.
If you have more than one screen, camera, or audio source, make sure you select the correct one from the drop down menu. Click the arrow to open the drop down menu. Is the audio too quiet? If you have connected a headset with mic or external microphone, check to see if it has been selected and you are not using the built in computer mic.
If you are still having issues,try rebooting the computer.