Mythos has been officially released today. That trailer was created to celebrate the occasion. Apparently, you probably shouldn't watch it if you're a noob.
You can download the MMO from the official website or, if you have any issues, via these mirrors . If you're more into your physical media you can purchase a boxed version that comes with £10 of in-game credit for a bargainous £9.97.
Even better, the kind people at Frogster have given us 50 boxed copies to give away. To be in with a chance of winning, post your own PC Gamer myth in the comments. The most legendary myths win the game.