Ask HN: Old US documentaries about aviation and X planes

[alea_iacta_est]

I remember watching some old US documentaries, in color, about the x plane prototypes and aeronautics in general, but I can't remember the name. Thanks

[hindsightbias]

https://www.youtube.com/watch?v=NNiZG_edpes

https://www.youtube.com/watch?v=RlS8HNQ94bc