Seems like a great deal. Next cheapest seems to be £12.93! I think the hmv image on the website doesn't explain just what you are getting. The catalogue number on the website is definitely the limited edition though.
It is also part of the 3 CDs for £10 deal, so make the most of it if you want!
Not sure if it is instore too.
Here's the CD/DVD info:
'A Cross The Universe' is the first live outing for French electronic duo Gaspard Auge and Xavier de Rosnay otherwise known as Justice. Rocking dancefloors across the world, this DVD documentary and CD captures the duo's ferocious energy - from DJ sets to live shows. Songs such as 'DANCE', 'Phantom' and 'We Are Your Friends' come to life, leaving the audience enthralled.'