...John's Wikipedia page: http://en.wikipedia.org/wiki/John_Clark_%28musician%29
 
...and these are a few YouTube & Facebook videos in which John / John's compositions appear:

the MJO at the Blue Note in Tokyo (April 18-23 2011) http://www.youtube.com/watch?v=w3G7Mpatfsw&feature=player_embedded#at=15

John's composition '747' in a really interesting performance! http://www.youtube.com/watch?v=jN-kI4b6_cs

John plays David Amram's 'Blues and Variations for Monk' http://www.youtube.com/watch?v=SvOUdXx-dgU

The Mingus Orchestra @ St. Bartholomew's, 2010: http://vimeo.com/20006956

B3+ / Sound Liberation at the Flea Theater: http://www.facebook.com/video/?of=670448372#!/video/video.php?v=225158902012&subj=670448372

Gil Evans Orchestra, 1976, Poland (I think....): http://www.youtube.com/watch?v=GO4YS8nVBvE http://www.youtube.com/watch?v=mqXoDURR1BQ&NR=1

Gil Evans Orchestra, 1983, Lugano, Switzerland: http://www.youtube.com/watch?v=yAFYeFLVx7U&feature=related

B3+ at the Chelsea Art Museum: http://www.youtube.com/watch?v=gItwtl5dcto The Mingus Orchestra at St. Bartholomew's Church, NYC: http://www.youtube.com/watch?v=9aUh47p31jo

More coming soon!