Here's an example of a requirements use case for a common activity: renting a video. Obviously, there are a number of other high-level use cases involved in the store's overall operation, but this case covers one broad process that's central to the store's business:
Requirements Use Case for Video Rental
The video store maintains an inventory of rentable videos for perusal by customers. A customer enters the store and browses the inventory to select any number of videos to rent.
The customer then brings the videos to the front counter where an attendant identifies the customer, makes note of each video, and calculates the total rental price. The attendant gives the customer an invoice, which lists the videos and shows the total amount due.
The customer pays for the rental and leaves with the videos. To avoid setting off the security alarm, the attendant hands the rented videos to the customer as they leave.