Microsoft had temporarily disabled Skype & Lync video calling during the Christmas holidays. Luckily Microsoft has released a new Skype version that enables this capability once again.
How to get this version?
Go to the Skype.com website and download a new version.
You will most likely get this version : 7.1.0.105 (at the time of writing)
If you get a different version then you should try to download once again with another browser to get another version.
Install Skype and make sure you are using the correct version.
Now Video Calling is available again
Example video call between Skype and Lync
Codecs in use between Skype and Lync are
Audio : RT Audio
Video : H.264
Happy testing.