The Live Earth Concerts were held in multiple countries, and I happened to come across the one for Rihanna, and I think she did a good job. She was on stage for 28 minutes straight, her act was good but there is room for improvement, but her music was great and I enjoyed it. Its a 349 MB file which can be found on TorrentSpy, especially worth watching if you like Rihanna.

Link: TorrentSpy