You know I always thought it was pronounce "SIde-real" like they're something next to reality, something outside it, which is why they can mess with it the way they can, they have a unique prospective of it or something. Was that just me.
Sidereal is an archaic word meaning "of the stars", the same way Solar means "of the sun" and Lunar means "of the moon" (and Terrestrial means "of the earth"). The pronunciation in the video is essentially correct. (A lot of the other info in this video is out-of-date as of the current edition, but the third edition Sidereals content is still very new).
