A new documentary about John Lennon has proved the hit of the Venice Film Festival so far, the singer-songwriter's rage against American involvement in Vietnam resonating with relevance to today's Iraq conflict. Lennon's genius as an artist/activist shines through in "The US Vs John Lennon," by documentary makers David Leaf and John Scheinfeld, which was warmly applauded at its first screening in Venice. Denis Barnett reports.