Yes, a skewb is a shape mod of a pyraminx, many people probably don't realise this as the two puzzles look so obviously different. However, it is true, a skewb has 4 fixed corners, just like a pyraminx, a skewb has 6 centres which are the equivalent of the 6 edges on a pyraminx and a skewb also has 4 other corners which are equivalent to the invisible centres in the middle of each side on the pyraminx. The actual purpose of this video was not to explain that but to explain how to reassemble a skewb and pyraminx as I feel, especially with skewb, it is something many cubers can't do. You can browse a huge range of pyraminxes and skewbs right here

You can also hunt down speedcubing.org's sponsorees who are good at skewb: Matthew Stephenson

Harry Owen

And pyraminx:

Rafi Niman

Joseph Archibald

Michael Pasanen