Typo, I think. He said "speed of sound" but used "speed of light" (which is actually a bit high for current in a wire, electrical current is normally closer to .7 light speed or thereabouts).

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8