A post in reply to a request for the dress seen in Professor Green's I Really Need you tonight vid.
Since the video is from a few months ago the dress probably isn't available any more and I can't find any info on it, there are however a few similar styles avaiable at the moment.
The closest thing I could see on UK sites was this Karen Millen dress. Gorgeous but rather pricey at £225 at asos.com.
US site Flirt Catalog has two very similar looks both featuring the black sparkles, similar neckline and low-cut backs. The plain one is $49.50 and the one with the chain neckline is $59.50.
Pics from their respective sites