The guy in the yellow shirt (“Reconstruction Continues . . .,” his shoulder blades informed) didn’t seem to notice how close the crowd was packed, how smoky the air was, or how generally unpopulated and accommodating the 9:30 Club’s main bar looked. Groovy 20-somethings crammed into the center of the floor (close enough to tell if the adjacent bodies belonged to nose- or mouse-breathers) but the bar remained unclaimed. A nice omen for the Beta Band to see that the attention was squarely on them, not the overpriced alcohol. Guy in the Yellow Shirt (heretofore GIYL), and everyone, really, was pretty happy to somewhat ignore the booze, let their brain shut down and their body spaz for the hour plus that the four boys from Scotland played. Spaz, spaz they did, in between gawking at the intermittently used video screen and sputtering through fits of motionlessness — utterly content immobility, sound tracked by appropriately entrancing folk-hop. The crowd ebbed and flowed as the Betas bounced through a set heavy with songs from their Three Eps and the more recent, fully realized and rewarding, Hot Shots II. Ignoring the occasionally brilliant tunes from the self-titled debut they famously despise was a regrettably wise choice, as they opted instead for the catchy, sporadic redundancy of the EP songs, and the tight-knit spastic smoothness of the Hot Shot cuts. It was either this or the ADHD free-for-all of the debut’s hodgepodge songs, and that might’ve been too much too handle. But fanciful, hypnotic slices of “Inner Meet Me” (with somewhat freakish picture footage of our fair four friends gallivanting across the ostensibly Scottish country-side, giddily amateur and Python-like in their carefree absurdity) and the haunting “Squares” had just enough reckless continuity to eat. Eat them, you could. GIYL seemed willing, yellow shirt a flutter with the idea of ingesting songs. And lead Beta Steve Mason’s antics made him and the music all the more tasty. Bouncing around from bongos to a second drum kit (on several occasions, but wait ) to the top of an amp, he was thoroughly excited and excitable, childlike in his urgency. At one point, he tried to spread the buzz and cheer up “the sad people” of the audience, as he saw them. He might’ve misinterpreted the stilted awe as a sign of boredom, but he would’ve been wrong. Still, feeling a lack of communal response from a moody crowd that did appear to be alternately disinterested and militantly mesmerized, Mason strummed into “Dry the Rain”, the uplifting epic from EP land, nee High Fidelity. His somewhat stretched, fuzzy roar reached its boiling point while breathing the song’s powerfully euphoric footnote, “If there’s something inside that you wanna say / Say it out loud it’ll be okay / I will be your light.” It would be all right. And who’s to argue — a voice so passionate couldn’t fake words that unremarkable and still make them bone chilling. But it was a collective high that carried the night, despite the crowd’s sometime stunned malaise. The seething bass of “Life” could disrupt the flow of blood through veins, and the fiery images on the screen behind the band were equally pulsating: helicopters bursting into balls of fire and the like, throbbing and mad. Nauseating if you’re the wrong person, and purely, thoroughly invigorating if you’re the right one. GIYL, shoulder bones akimbo and slithering, was all right. The set ended with a glitzy version of “Broke” (one of the better singles of 2001), and the throbbing finale left the capacity crowd eager and unsatisfied. So, after a thunderous session of clapping, the Betas emerged from the side of the stage to pound out three more tunes. “Al Sharp” and “She’s the One” kicked off the encore with a great punch, but it was the closing version of “The House Song” which will remain one of the better live spectacles. From the incessant sample (“Put it your pocket for a rainy day, sing a song, and you know you’re wrong . . .”) to Mason’s bawdy French rapping, the song evolved into a vibrant four person beat factory, each man banging away on his own drums, or drum likeness. The epitome of climax. And the entire performance felt indeed like a group orgasm. The images on the semi-frequently used fourth grade class pull down screen — sporadic, hallucinogenic, silly. The exchanging of instruments between band members and their subsequent hijinks, drum-offs, and off-kilter noodling. The lyrics, the beats, the whole attack, relentless like a coddling stampede. Exhilarating and calming, all at the same time, enrapturing like a car accident involving unicorns. GIYL was smiling, and the whole room smiled along, smoking a collective, cliched cigarette.