PRIVATE PRACTICE - "Blowups" - Two back-to-back episodes of "Private Practice" air on THURSDAY, DECEMBER 3. In the second episode, "Blowups" (10:00-11:00 p.m.), a terrible explosion at Dell's house lands Betsey and Heather in the hospital, and everyone is pushed to the limit trying to save their lives. Tensions rise even higher between Addison and The Captain when her mother, Bizzy, shows up and a shocking family secret is revealed. (ABC/CRAIG SJODIN) AMY BRENNEMAN, TIM DALY