Klaus is talking to Rebekah, telling her about Bonnie and how she is always on his mind . The rest is pretty much Klaus giving Bonnie an ultimatum 'choose me of your fire, be mine of u will burn'.
If you've seen the film Savages then this is the VD version of it with Bonnie as the main character. If u haven't seen it then u get the gist of it and it's a pretty amazing video :)
Kat talks about the prank @8:10 but doesn't say who pranks her...in the video of Joseph @ Eyecon he says it was him @11:00....PS Kat and Steve are ADORABLE! I will never ship Beremy but I wouln't mind KatQueen! LOL!
We never know when it begins. Klaus and Bonnie are enemies but they began to have conflicting feelings to each other. Diclaimer: I own nothing, only my deep love to them. Music: Adele, Skyfall