ORIGINAL: B58
That clip was shown in tech school at Chanute when I went through there in 1966. It was a result of a pair of pliers being left in the inlet. The engine, a J-57 if I remember right, was damaged, and the result was the accident you saw. On take off I think. The flame out the tailpipe was a result of the engine coming apart. I also remember that the seat would only work above 300 feet? Think that was right. My 2 cents.
It's interesting to hear how many different ways that accident happened. I have heard it was an inexperienced pilot, a test flight early in the program, just regular pilot error, but I had never heard of FOD. I'll add that one as well. The test flight explanation seemed plausible given the video I have seems to be taken in the desert.
I am actually suprised that I can find the video or a still of this infamous flight.