"To get back to why visuals; this was just an experience. Somebody about five or ten years ago played me a black&white video tape of a concert by Miles Davis in a theatre in Philadelphia. It was Coltrane, Cannonball, Bill Evans, whoever. This was a single camera on the first balcony, that just turned to the left for the piano solo, to the center for the trumpet and saxophone solos, and to the right for rhythm section solos. The concert lasted an hour and a half. They used a long lens so that you could bring in closeups." 

While it would be marvelous if such a document existed, evidence suggests that Bley's memory is flawed, and that he is remembering a later concert, perhaps conflating several videotaped performances by later Miles Davis groups.

--Bley's personnel listing is vague ("whoever") in the original interview
--The period when Bill Evans was a member of the group is fairly brief, and so far we have not found evidence of a concert by that group in a theatre in Philadelphia in 1958 (the session number 58-1000 simply indicates the ending date of that group's existence).
--Bley says "video tape", which would not have been an option for other than a professional, commercial broadcaster
--To film a 90 minute concert using 16mm film (the commonly available technology) would have been VERY expensive and would required two cameras because the film reels ran out every 20 minutes.
--we've found no other report of such a film, which seems unlikely given the complexities involved in making such a film.