Alex loves to play chords, and lots of them! He doesn't use bar chords a whole lot, mainly triad shapes that allow him to play many chord voicings over the neck of the guitar and resolving to the next chord with as little movement as possible, like a piano player would do. This technique is also used eclusively by Hendrix, VanHalen, and Rhoads.
I'll try to give you an example of what I'm talking about. Suppose the chord progression was G to D, this is one way of doing it using triad shapes and voice leading. The chord tones are in parenthesis (sp?)
G chord: 1st finger, 2nd str., 3rd fret (D), 2nd finger, 3rd str., 4th fret (B), 3rd finger, 4th str., 5th fret (G)
D chord: 2nd finger, 2nd str., 3rd fret (D), 1st finger, 3rd str., 2nd fret (A), 3rd finger, 4th str., 4th fret (F#)
You'll notice you will be able to make this change extremely fast, and it will have a different sound then if you used bar chords or open str. chords, it's called voice leading. Good Luck