The weekend starts this evening with Mahler's Symphony No. 2, "Resurrection," conducted by Michael Tilson Thomas (who was an assistant conductor of the BSO way back when). James Levine would have conducted if he hadn't been recuperation from back surgery. The performance will also include Layla Claire, soprano, Stephanie Blythe, mezzo-soprano, and the Tanglewood Festival Chorus.
Saturday evening brings an all-Beethoven program with Rafael Frühbeck de Burgos conducting the King Stephen Overture, Piano Concerto No. 3, with Gerhard Oppitz, piano, and Symphony No. 5.
On Sunday afternoon Maestro Frühbeck returns to lead the orchestra in Mozart's Serenade No. 6 in D, K.239, "Serenata notturna," and Violin Concerto No. 5 in A, with Pinchas Zukerman as soloist, and Ein Heldenleben, by Richard Strauss.
BTW, a note on the BSO Tanglewood schedule page indicates that WAMC will broadcast/stream the Sunday concert. Dunno about the others.
Finally, check out this video. The note seems to be wrong about the singer's age. Elsewhere, I find he was born in 1992 and this performance was in 1995. Also the source says his voice changed a few months later. Apparently this is an aria that the No. 1 treble of the choir often sings at these family concerts. But, corrections to background info aside, I think he does a sensational job.