https://www.youtube.com/c/AndreasSpiess
Andreas Spiess has videos on many RF related topics.
https://www.youtube.com/c/LOOKMUMNOCOMPUTER
Sam Battle has a ton of synth and MIDI projects and runs a museum in the UK that houses a boatload of interesting stuff.
https://www.youtube.com/c/DavesGarage
Dave Plummer is a retired M$ employee (beginning in the Win3.1 days) and his videos cover a lot of early personal computer development.
https://www.youtube.com/user/mikeselectricstuff
Mike Harrison does LED art installations and has videos detailing how he designs and builds controllers for them. He also loves to take stuff apart and has an interesting web site.
https://www.youtube.com/user/lightman500
Brian Lincoln has lost of videos detailing his many animatronic projects.
https://www.youtube.com/c/timhunkin1
Tim Hunkin has built many interactive art installations and has a great video series on all sorts of components he uses.
https://www.youtube.com/c/halstaff
Steve Koci (who sadly passed away in 2021) has all sorts of videos on DIY animatronics.
https://www.youtube.com/channel/UCOG6Bi2kvpDa1c8gHWZI5CQ
Cine-Lights has many examples of LED projects.
https://www.youtube.com/c/Bigclive
How can you not like Big Clive!!