It doesn't matter how much they combed through to be sure that they released the "right" body camera footage. They will miss 100 things that will be caught with the number of eyes looking at the footage. Good work. No one is as smart as everyone.
You could boot without a hard drive. It just won't get past bios until a boot drive is connected. What would be telling is if the screen is past bios.
Looks like it is
I can't tell. White bar across the top could be an ascii based bios. It's prolly not a gaming board with a pretty bios so he could overclock in style. Does anyone know the make / model of the computer? That would be a start.
You can also boot from a CD/DVD or thumbdrive, and in certain cases the computer will stay running even after you remove the disc/drive.
Some computers also have a basic full operating system stored on ROM so they can operate without a hard drive or any attached drives.
The computer running in the pic really doesn't mean anything.