I think the footage you are talking about is a piece of footage by film maker Jonas Mekas. Jonas Mekas who specializes in, and is known as "the father", of the Avant Garde style of film making left what he shot unused in film form, to the best of my knowledge, until 2006 when he was asked to prepare a short film involving the music of Mozart, for which he won an award, for the Vienna film festival that year. He chose to combine Elvis and Mozart and in my opinion the result is stunning and has to be seen to be completely understood as Jonas increases the speed of the film whilst merging it with other shots in his unique style. I think this is what you saw, perhaps without audio, perhaps even slowed down a little or with MSG audio added as I know a couple of different versions were edited by fans from the original clip that was released.
Since the festival Mekas used stills from his film of Elvis to present in the Maya Stendhal Gallery in New York. See pictures below. What we have available is a few short minutes of the show heavily edited and sped up to create the effect he wanted. It is likely that the whole film is longer than that which has been released because of the scope of the show recorded, right from beginning to end. Of course this is uncertain but it seems reasonable to think that more was shot than made the final edit. This footage was shot on 16mm film. [/size]
Not only did he exhibit stills from the film in New York, he also featured them in a project called "The 16mm series" in Tokyo. You can see a picture of this below:
Take a look at this shot of the footage itself. My source of this film is reasonable quality yet unfortunately I is not in the same league as the master shots of which you can see underneath that.
As you can see, the quality is excellent on the second image, due to the fact that it is from the first generation source. The runtime of the film that has been released is 3 minutes.