Default Have a seperate account for Instant Video?

I have a rooted Kindle Fire HD 7-inch. Is it possible to have a separate account just for Instant Videos? I have an account that has Prime on it and I have another account with all my books/games that I've purchased. The account with all the games/books is the main account. I would like to be able to access my Prime Videos account as well. Is it possible to change the account on just the Amazon Video app? Anything I can modify or hack?