Here’s a bunch of Youtube channels that feature footage from old hardware. Add your own.
The No Swear Gamer. Mostly consoles, going back to the 70s, some Atari 8-bit computer (NTSC)
Nerdly Pleasures. From the blog. Mostly old computers, but also some console stuff (NTSC).
MSXFAN. Mostly features MSX (doh!), some console vids. NTSC (South Korea).
necronom. 8-Bit Pal computers, goes back to the Commodore PET.
Zeusdaz. Mostly 8-16 Bit computers (PAL), some console vids, Arcade is emulated.
Steve Benway. Mostly followed this guy because of his (by now ancient) footage of obscure PAL computers (Dragon 32, Memotech).