It's a bug.
I am trying to place video calls from an iPad 2 to a laptop PC with a Logitech c310 webcam. During the call I have the iPad in landscape position. When the call begins the incoming picture on the laptop is in landscape mode, which is what I want. After 20 seconds or so the picture spontaneously rotates to portrait mode, which is what I don't want. I can't find a way to change the picture orientation back to landscape mode. I called Apple support and, after trying a few things on the iPad, they said the problem must be with Skype. Does anyone have a solution to this? Thanks.