Bay Street Theater in Sag Harbor will open its East End Music Film Series on Sunday at 2 p.m. with a screening of Sharyn Felder’s “A.K.A. Doc Pomus.” Hosted by Suzy Elmiger, an accomplished film editor, the series will also feature D.A. Pennebaker’s “Company” and his first film, “Daybreak Express,” on Feb. 7 and “Voices of Sarafina!” by Nigel Nobel on Feb. 28, both at 2 p.m. All three filmmakers will be present for the screenings.