Verdi: "Falstaff." VAI. $69.95. This memento of Glyndebourne in 1976 should not be confused with Goetz Friedrich's studio version, recently telecast by PBS. Jean-Pierre Ponnelle's restrained, small-scale, British-flavored "Falstaff" served as a model for a rowdy San Francisco Opera blow-up last season. The late Donald Gramm seems tentative at times, but dominates as a generally poignant, lyrical, not-too-fat knight. His chief colleagues (Kay Griffel, Nucci Condo, Benjamin Luxon, Elizabeth Gale) sustain respectable routine under the dainty musical leadership of Sir John Pritchard.