I agree with the note above about Sonar X3 Explained as being very similar in content to the X1 and X2 versions of Explained, with of course some updates that are specific to X3.
The Sonar X3 New Features tutorial, however, is very helpful, and it's extra affordable at the moment in the Cakewalk store.
That said, I highly recommend any Groove 3 tutorial, and especially the ones offered from Eli Krantzberg. He has a really good approach to getting capabilities and the how to of each tool covered.
If you want to watch the tutorials while connected to the internet, I concur with sharke that the online subscription is one heck of a great value. In my case, the time I have to watch these tutorials (which can be 3-4 hours each), tends to be time when I'm not connected to the internet. So, I do prefer purchasing them (especially on discount) and going through them offline. Groove3 has had some very generous discounts over the past year at various times.