Watch BBC Proms: Sondheim's 80th Birthday for Free: How to Stream the Movie Online at 123Movies. . Marking the 80th birthday of one of Broadway's great innovators, the first ever all-Sondheim Prom at the Royal Albert Hall. The concert includes excerpts from hit shows A Little Night Music, Sweeney Todd and Into the Woods performed by a starry cast of leading figures of the opera and theatre worlds with Bryn Terfel, Maria Friedman, Simon Russell Beale and some special guests. Also on stage is the BBC Concert Orchestra conducted by David Charles Abel. Introduced by Katie Derham.