Documentary footage of a Hollywood Recording Session in 1969. I think there are some famous "Wrecking Crew" type players in there. Isn't that Earl Palmer on drums? Start naming 'em :)
UPDATE: I followed some links back from sites linking to this post and found out the following: They're actually recording an LP, not soundtrack music ( I think I can be forgiven for thinking that though), and it's The Plaster Caster Blues Band - ST (1969).
The personnel according to this site (who I assume took it from the liner notes) is Bobby Bryant (Trumpet), Arthur Adams (Guitar), Jules Chaiken (Vocals), Max Hardy (Drums), Gildo Mahones (Organ), Gildo Mahones (Piano), Gildo Mahones (Keyboards), Ellen Sander (Vocals), George Harmonica Smith (Harmonica), George Harmonica Smith, Clifford Solomon (Saxophone), Clifford Solomon (Tenor (Vocal), Bob Thiele (Producer)