Ah, the immediacy of the web. On December 10 — that is, yesterday — the nimble, concept-minded techno act Underworld — easily among the best songwriters in electronic music, however small a field that may be — performed live at the BBC Maida Vale Studios in London for an audience that reportedly numbered around 50, all for broadcast on the radio show of legendary disc jockey John Peel. And now, the full, hour-long performance is up on the web (here). There are extended moments of bracing, mechanized revelry, and plenty of fan favorites, including “Jumbo,” off 1999’s Beaucoup Fish, the Trainspotting hit “Born Slippy,” and “Trim,” off last year’s A Hundred Days Off, with its bluesy guitar by member Karl Hyde. The BBC/Peel site also features a dozen or so photos of Hyde and bandmate Rick Smith performing (the group’s DJ, Darren Emmerson, left following the release of the band’s live album, Everything, Everything, in 2000).