In this video of a more complex cockpit, belonging to the SR-71, why don't we see any windshields? Were they not required for the SR-71, or are they not captured in this video? If windshields were actually not there, then please elaborate why!
There are forward-facing windows in the SR-71. The image you posted is just of the instrument panel. The windows are better visible in the photo below. This is from a simulator but gives a better idea of what the cockpit looks like when in flight.
The windows and cockpit are small due to the high speeds and altitudes that the plane is designed for, making the cockpit resemble a smaller fighter plane.
As a side note, there are planes without windshields, a notable example being the Spirit of St. Louis.