1. 2-3 minutes' worth of a concerto movement 

2. Orchestral excerpts:

* Mozart Symphony #35 (Haffner) mvt 4, 134-81

* Mendelssohn Midsummer Night's Dream Scherzo, N to O

3. Orchestral solos

* Brahms Piano Concerto No. 2, mvt 2, 71 to the end

* Rossini William Tell Overture opening to 48

All excerpts are available legally on IMSLP.