You must have a different version of the Virgin Media website, can't find any details whatsoever for adding from there.
I subscribed directly with Premier Sports for £99.99 and the picture quality casting to my Shield is better than S4C for the same game and much better than Sky Sports "HD" of course.
Somebody at Virgin Media needs better negotiating skills. £9.99 via Sky with access to the Player app, £12.99 via Virgin and no Player access.