I love this song! I think it's heard first at episode 330 where on the previous episode, 329, Naruto met and conferred with the bijuus and their respective jinchuurikis. Kabuto (let's face it, it's more like Kabuto's the only enemy now and he's pulling all the strings) reanimated all the jinchuurikis after they have died having the tailed beasts pulled out of them.
I have noticed though that the one tail and it's wielder aren't with the group. That could probably be because Gaara, the one tail jinchuuriki, was restored back to life after the "monster sucking event" of the Akatsuki. Still, wouldn't the ichibi be present?
In the scene inside Naruto's subconscious, like most meetings with the kyuubi, he met with the tailed beasts lot where he was introduced to their personal names (shocker, even the kyuubi has one) and was assumed to be the promise lad their old master had spoken of. Seems like Naruto has more pressure now on his shoulders. Lol.
We also see on flashbacks and even on this song's video of the cute chibi/baby looks of the bijuu. Yiiiii! Kyubii looked like a tame, very adorable pet. Hehe. Don't let him hear me say this though. Lol.