I have tried 3 other types of tabs extensions in my attempts to align the content types offered by K2 component in tabs structure. All other extensions required that I implement their code in the k2 item templte. Only this one worked out of the box. With a touch on the template I was able to style the tabs the way I want, and was able to hide the tabs that were empty.
Then I had trouble with showing video in a tab in responsive template. The developers were extremely fast and helpful in the forum provided to support the extension.
I fully recommend this excellent addon to K2 that has no alternatives so far.