If you bought the deluxe box edition of In Rainbows just for the session leftovers, you did not get your eighty dollars’ worth. Two tracks are just a minute each of Kid A-style weird science. But “Down Is the New Up,” “Go Slowly,” “Bangers and Mash” and “4 Minute Warning,” all premiered on Radiohead‘s 2006 tour, are the kind of outtakes other bands would kill to have as A sides. “Bangers and Mash” is still as it was onstage: a headlong rush of double drumming and tangled, whooping guitars, like a Chinese spin on Captain Beefheart‘s Magic Band. “4 Minute Warning” is not as Spartan as it was live. Thom Yorke’s haunted-church piano and high-tenor worry are now dressed like a space-plantation blues, with guttural guitar and ghost-choir voices. Of the older songs here, “Up on the Ladder” is a Kid A refugee with rude guitar and a goosestep beat while “Last Flowers” was cut, under another name, for OK Computer. It has a lonesome-piano intro and Yorke pleading with full-frontal desperation: “I can’t face the evening straight/ And you can’t offer me escape.” Apparently it’s too simple and naked for an official Radiohead album. But it deserves to be on record. Now it is.