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 :)