Before your interview, take some time to gather data related to the budgets you have worked with, and the times when you have come in under budget. This way, you will be prepared with specifics when asked about your budgetary experience.
The interviewer wants to see that you have great insight when it comes to being budget conscious. Appropriate planning is one of the keys to a successful project, so be sure to discuss the steps that you take to plan a project's dollar spend carefully.
Every dollar counts, even if you are working for a massive media conglomerate like NBCUniversal! If you do not have experience in budget management, refer to the fact that you are responsible and resourceful.