That channel owner, Ben Katz did the mechanical hardware, motor control PCB + firmware for the MIT Mini Cheetah as part of his PhD, here is his blog post on it[1], which links to a full technical report. The latest firmware is here [2]

[1] http://build-its-inprogress.blogspot.com/2019/03/hello-there...

[2] https://os.mbed.com/users/benkatz/code/Hobbyking_Cheetah_Com...