The HTC Vive, a virtual reality headset created in conjunction with Half-Life and Dota 2 developer Valve, begins shipping today to people who placed their pre-orders last month. It's exciting!To me, though, the most compelling part of the Vive's launch is a short video that Valve released today that solves the single biggest problem facing VR as a whole: convincing people that it's worthy of their hard-earned money without them needing to try on a headset.The video—technically part of a series of videos that Valve published this morning on Steam, its iTunes-like digital distribution system—demonstrates what's known as "mixed reality," or VR footage combined with video of people trying out the games. Among other demonstrations, you'll see real people standing in front of a green screen using the Vive to play a virtual game of fetch with a virtual dog (with the in-game footage appearing on the green screen), and real people shooting a virtual bow-and-arrow at Clash of Clans-style invaders.It's the closest you'll get to understanding the immersion offered by VR short of borrowing a friend's headset.But just like the Oculus Rift last week, most early impressions of the Vive are mixed, with critics bemoaning a lackluster library of VR games at launch and noting the high cost to get your foot in the door. It costs $799, and you'll need a powerful gaming PC (which can run you more than $1,000) to use the thing. But the promise of VR is there for all to see, with apps from companies like IKEA ( you can now design your next kitchen using the headset) demonstrating VR's non-gaming capabilities.