No app trailers is avaiable on Apples and Android devices. When using a apple device i dont know if the offer itunes cards but they do use PayPal which is what i use the majority of the time.
I tried to get free gems using the method you suggested & could not get it to work. Is this only for apple devices? Did you download app trailers from google play store?
Sigh. They need to make my mailbox bigger o.O Cleaned it out so I have room.
I am a experienced player that knows almost all you can about camelot. If you have a question feel free to ask.