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.
There actually are USB to aux cables out there, but it's important to understand what they're for and what they can't actually do. If you have a USB thumb drive, for instance, and you want to plug it into your head unit, you'll need a head unit that actually has a built-in USB port. Plugging it into a USB to aux cable, and plugging the cable into the head unit, isn't going to accomplish anything at all.