Bido,
If you work out some major scales using the tone tone semitone tone tone tone semitone pattern you will see that all of the other major scales besides C have sharps & flats. That might make things more clear for you.
i) Every note in an octave (12 of them) has major scale associated with them.
ii) Every scale, major or otherwise can be played in multiple places on the guitar.
To say that this first position c major scale is THE C major scale is right and wrong. Yes it is a C major scale (the first position one) but there are many other places that a C major scale can be played (or found) on the guitar, and they are all equally C major scales.
And same goes for the major scales for all the 12 notes in an octave.
I hope this helps you out. if it doesn't then I would suggest watching the Acoustic Genius again. There is a lot of information there.
Beaker.
