A one-man show, by definition, is a daring high-wire act — a lone figure onstage, commanding an audience through sheer force of will. In William Gibson’s play “Golda’s Balcony,” that tension between strength and vulnerability mirrors the situation of Israeli Prime Minister Golda Meir, alone at the helm during the Yum Kippur War. Jeremy Kagan’s green-screen filmization, in its over-busy editing, ever-changing angles and constantly shifting backdrops, strips the play of its starkness, leaving disproportionate schmaltz and propaganda. Pic, which opened Oct. 10 at Gotham’s Quad Cinema, merely hums to the choir.Actress Valerie Harper initially seems kitschily arch, reducing Meir’s destiny to a cross between Yentl-like women’s lib and Molly Goldbergian Zionism. As pic progresses, though, Harper’s mannerisms, interestingly counterpointing helmer Kagan’s impressionistic wallpaper (composed of original artwork and digitally augmented archival footage), become more finely tuned, in time for pic’s nuclear climax and Gibson’s portrait of a woman and a nation willing to destroy the world in search of peace. Play, which first appeared in a full-cast version in 1977, has been reworked twice since, and perhaps it’s time to apply Israel’s mantra, “Never again,” before it becomes a musical.