Ye Gods there are some idiots in the video comments.

"The military during the Civil War, also did not want repeating rifles, this trend remained until the Great war,
only after they were being wiped out by the German repeating arms. We were also slow in adopting machine
guns until the Mexican American war when one of the Generals mounted them on automobiles on his own, not
with the blessing of the Army."
Da Fuq?

Yeah, right the US Army and Marine Corps were still using single-shot rifles in WWI.

Whatta maroon.