Feynman's friend Ralph Leighton wrote about Felnman's long-standing desire to go there [1]. The BBC Horizon programme had an episode called "The Quest for Tannu Tuva" [2] which might be on youtube.

[1] http://www.amazon.co.uk/Tuva-Bust-Richard-Feynmans-Journey/d...

[2] http://sciencek.com/video/1151/horizon-1988x25-the-quest-for...