As the original Birkin bag goes up for auction at Sotheby's in Paris, we discuss what this original prototype is expected to fetch for. We also take a look at how this iconic handbag came to be: thanks to the late Jane Birkin's clumsiness and a chance encounter on a flight in first class. We also discover how near-identical knockoffs, or "superfakes", are making it harder to check if a luxury bag is the real deal or a counterfeit version.