@Imagine: If I were to cast, I'd put it in a lobby pause. Those are long and there's generally not much going on. Of course, having to flash a code on screen is definetly a nuisance.
@Gilder: Most definetly, a risque photobook featuring Keyvias would only change gaming for the extremely better. Jokes aside, most casters already do it in bigger games. I remember one instance of some alcohol-based gaming channel handing out exclusive skins in League of Legends. Remember, people love free stuff.