This video was produced for the CIA c/a 1956-57. It was made for showing to the very few senior leaders who were cleared for the program at that time.
https://www.youtube.com/watch?v=uvJim_o7Dp0
There is a sequence showing the high speed taxi test a few days before the official "first flight".
The aircraft in the bogus Lockheed Martin "first flight" video referenced by Jhieminga
bears the marking "344" at the tip of the vertical fin. Article 344 was not delivered to the test site till 20 November 1954, nearly 4 months after the first U-2 flight.
Parts 2 and 3 of THE INQUISITIVE ANGEL are here:
https://www.youtube.com/watch?v=iTNKqQum4e0
https://www.youtube.com/watch?v=yRoC0Lo8Ylw
In total, almost an hour-long discussion of the aircraft and its reconnaissance systems