With Valve’s Steam Machine prototype boxes now in the hands of lucky beta testers, it’s only natural that videos have started popping up on YouTube. After the unboxing vids, it’s time to move on to booting the system and showing off its Linux-powered gaming prowess.Corey Nelson is one of Valve’s chosen few, and he’s been busy with his beta box already. In one of his first uploads you can watch the system boot — which takes about 30 seconds to go from power on to the login screen.During startup you might notice the Asrock logo — they’ve provided the mainboard for Valve’s prototype. Indie hit Don’t Starve gets taken for a test drive first, and Valve’s unique dual-trackpad controller seems to work well as a mouse replacement during play.Next up: Portal and Left 4 Dead 2, which require a bit more of the Steam Machine prototype’s muscle. As you can see, the quad-core Core i5-4570 and 3GB Zotac GTX 780 video card are more than up to the challenge.It’s important to remember that this is still just a prototype. The hardware Valve has shipped to testers will provide them — and other companies that are building Steam Machines — with valuable real-world feedback.Actual retail-boxed Steam Machines may feature very different hardware configurations… and of course you’ll be able to build one yourself.You can do it right now, if you want to. Just be aware that Steam OS is still a beta product, too. You should expect the unexpected for now, but also know that things are only going to get better. Valve will continue tweaking the OS and drivers, and developers will bring more new games to Steam’s Linux library.