This wonderful video really helped me fall in love with Mahler's music a while back. The DVD contains two features, each a little over an hour long.
"Conducting Mahler" features Chailly, Haitink, Abbado, Rattle and Muti discussing Mahler and rehearsing with the Amsterdam Concertgebouw, Berlin Philharmonic and the Weiner Philharmoniker at the Mahler Festival in May 1995.
"I have lost touch with the World" is based on Mahler's 9th. It features Mahler biographer Henry-Louis de la Grange. It also shows Chailly conducting parts of the 9th with the Concertgebouw in his last performance with the orchestra in 2004. This DVD really got me into Mahler and Chailly's recording of his work.
Highly recommended to any Mahler freak out there who has not seen it yet.