It's something that you probably never expected to see, but with the end of the Mass Effect series and the ever-reducing possibility of a Wesker appearance in Resident Evil 6, voice actor DC Douglas decided it was a good time to say goodbye to two of his best-loved characters. He played Legion in Mass Effect 2 and 3, and Wesker in Resident Evil 5 and the Wii spin-offs.
It's a great farewell, I'm sure you'll agree. The scenes have been put together nicely and you're left with something genuinely funny. If you're trying to avoid spoilers for the Mass Effect games or the Resident Evil games (especially if you're avoiding Resident Evil 6 promotional material), you're probably better coming back at a later date.
Still, be sure to save it to your favourites, and fingers crossed somebody somewhere is commissioning a Wesker-Legion sit-com as we speak. And, if John St John is reading this, Duke Nukem and Big the Cat crossover, please.