The debut CD by the Welsh septet Los Campesinos! is packed with so much youthful energy, it oughta come with its own supply of Ritalin. Like the Go! Team — another group of coed U.K. kids who dig exclamation points and pep-rally cheers — Los Campesinos! play vigorous indie-pop, spiked with the sounds of glockenspiel and other instruments that require pounding. Not so surprising, Hold On Now, Youngster . . . has a bit of trouble staying focused. "Broken Heartbeats Sound Like Breakbeats" caps three minutes of breathless shouting with a gently swaying, out-of-left-field coda, and "This Is How You Spell 'Ha Ha Ha, We Destroyed the Hopes and Dreams of a Generation of Faux-Romantics" is as relentless as its title.