It's Rika Adachi (足立梨花) from the DVD with product code TSDV-41428. As for gravure idols with great behinds (not necessarily featured in the video); Minami Yuki (優希みなみ), Hikari Maeda (前田光璃), Isa Aoki (青木衣沙), Miho Sugaya (菅谷美穂) and Yuuri Haruki (春希ゆうり) Maybe I'll add some later on.