By Guy Tabachnick (photo of Lucy and Friends in Rivoli, Italy in a Displaced Persons Camp, ca 1946-47. Taken from www.lucymandelstam.com) Last week, my mom sent me video of her mother’s testimony given in 1989 at Yad Vashem, Israel’s Holocaust memorial. It’s on YouTube now, in three hour-long sections: my grandmother’s childhood in Vienna; the…