I have nothing against instructors using the name of a military unit to sell either their own hand-to-hand combat system or one that is used effectively by that unit. Not at all. For the most part, I see this as a marketing thing and each instructor/author has to make decisions on that front.
If you want to connect a USB device to an HDMI device then you must use a converter box. This is a set of electronics that change the protocols and signals. The only adaptor which works is the DVI-HDMI ones.
One of the best things about USB is that you can use any device with any port, the only limitations are the speed of the slowest device. If your Mac has super speed USB 3.0 ports, then plugging in an older USB 2.0 hard drive will result in USB 2.0 levels of speed, but the drive will still work.