MTV's new series 45th at Night is a nice addition for the music network, and posting the intimate, live-concert video online for free ain't bad, either. But the big props go to Amy Winehouse for delivering a gripping performance that speaks to her jazzy chops and assured-yet-sensual stage presence. Joined by an ace band including a horn section and male back-up singers, Winehouse performs material from her acclaimed album Back to Black. A throwback in the best sense of the word, she toys with phrases and messes with the arrangements while never undermining the emotional heft of such soulful gems as the title-track and "Love is a Losing Game," which features a smart cameo from Mos Def.  Check it out on MTV.com