Anthony McGill, New York Philharmonic principal clarinetist, launched a new mini-genre of musical protest on May 28 when he tweeted a video of himself playing “America the Beautiful,” transposed into a minor key, in honor of George Floyd, Ahmaud Arbery, and “the struggle for justice and decency.” David Patrick Stearns surveys some #TakeTwoKnees responses and some similar musical repurposings from earlier years — from Leonard Bernstein’s famous Beethoven 9th at the fallen Berlin Wall to Jimi Hendrix’s “Star-Spangled Banner” at Woodstock to Judy Garland on live TV transforming “The Battle Hymn of the Republic” into a funeral march for JFK. – WQXR (New York City)