This should help.. http://forum.wordreference.com/showthread.php?t=1054658
Beide and beiden mean the same. The difference in usage depends on the presence of the article (die/der/das etc.) before beide. If article is present, then use beiden. If there is no article use beide or end beide with case endings as in beider.
"ihr" (not capitalized) is the plural of "du" , the informal you: A mother says to her two children: "Ihr beide, kommt (ein)mal her!" The capitalized "Sie" is the formal you. You can use it almost like "you" as polite address to everyone perhaps except for children and your friends. Using the "Sie" is not difficult.
If I go by this site:
Then it says you can only use "beide" if there is no article (strong declension). If there are indefinite or possessive pronouns then you have to use "beiden" (mixed declension). So I just want to be 100% sure, "Ihr" here is a personal, and not possessive, pronoun correct? Is that why the answer is "Ihr beide"?
Ihr means "you" but plural. It is the informal 2nd person plural pronoun, i.e. "you all" as in "you all are young"
Beide means "both" or when talking about two of something
Bitte means "please" and comes from the verb "bitten" which means to request/plead/ask for, as in "ich bitte" "I request"
"Ihr beide, bitte" means "Both of you, please" or "You two, please"