Join us every Saturday as we create arty Halloween costumes based on our favorite blog posts of the week, in retrospect.

— In retrospect, Ai Weiwei’s parody of PSY’s viral rap video “Gangnam Style” — which instantly overshadowed another parody thereof starring a Paul McCarthy sculpture — may be our favorite piece of video art of the year.

— In retrospect, it might have been easier to get a good look at the auction record-setting version of Edvard Munch’s “The Scream” at Sotheby’s than it is in MoMA’s new exhibition devoted to it.

— In retrospect, we’re not surprised that the battle between Dallas’s Nasher Sculpture Center and the neighboring Museum Tower condos over the latter’s laser beam reflections has heated up.

— In retrospect, if Republican presidential hopeful Mitt Romney plans to keep denying the significance of his Massachusetts healthcare reform bill, he probably shouldn’t have insisted it be included in his gubernatorial portrait.

— In retrospect, all our Halloween costume how-tos — including “The Scream,” Damien Hirst’s “Verity,” Michael Heizer’s “Levitated Mass,” Cecilia Gimenez’s “Beast Jesus,” and Rob Pruitt’s “The Andy Monument” —  are a little too complicated, and we’ll probably end up going as “Gangnam Style” Ai Weiwei.

— Benjamin Sutton

Tags: Ai Weiwei, Edvard Munch, Gangnam Style, Halloween, In Retrospect, Mitt Romney, The Scream