Britney Spears dressed in black knee-high boots and a butt-skimming black mini-dress (left) to shoot her new music video yesterday. The 25-year-old singer, who also sported a black veiled hat, began filming the promo for new single 'Get Back' in a Los Angeles warehouse. A witness said: "Britney was strutting around the set in such a bizarre outfit - she looked like a cross between a hooker and a widow."The dress was so short you could see her butt cheeks!"Less than 24 hours earlier, Britney was seen stripping down to her underwear and jumping into the sea for a quick dip.The mother-of-two - currently in the process of finalising her divorce from Kevin Federline, who is father to sons, 22-month-old Sean Preston and Jayden James, 10 months - was house hunting in Malibu when she decided to go for a cooling swim in the ocean.With no swimwear available Britney pulled off her dress and splashed around in the waves wearing just a hot pink bra and tiny pink panties.