There are many extra features on this disc.
Among the 2 main features is a recording of a classic performance of 'beat poets' incl. Ginsberg. There are some poetic gems there.
However, for me what makes this disc really worth buying is Whitehead's documentary recording ('Benefit of the Doubt') of Peter Brook's classic and unsung play "US" (which was later transformed into a film called 'Tell Me Lies: a film about London').
Brook's theatrical event was a highly controversial phenomenon which was a whole-hearted and gutsy attempt for him and his group of actors, writers etc to produce an experience of the Vietnam war as lived through the eyes, feelings and thoughts of the British people. Whitehead's recording as seen here gives a very real flavour of how that experience was played out in the theatre. He also includes a few interviews with actors and Brook, but mainly (and wisely) lets the 'play' speak for itself. This is very powerful stuff.
I was lucky enough to see the film "Tell me lies" shown in London recently. Sadly it is not available on DVD. This current disc would make a good complement to its release.
Needless to say, the themes raised are very relevant to our times in the early 21st century - this is certainly not the stuff of '60s archive curiosity'. Not easy viewing, but certainly thought-provoking and enlivening.