This FAQ will help you to:
You can switch cameras during a video call, or you can turn off your video and continue the call with audio only. Simply tap the video icon and select either Front Camera, Rear Camera, or No Video.
PS Vita to PS Vita video calls use the full screen, but video calls from other versions of Skype may not fill the entire screen.
For full screen, simply tap the Full Screen icon at the bottom right of the screen.
This enlarges the image, but also crops the top and bottom of the image.
You can scroll up or down to see the cropped areas, or return the image to normal by tapping the Resize button .