Amazon.com Inc. is adding NBC shows to its roster of free videos that can be watched online by customers who pay $79 a year for unlimited free shipping on goods bought at the online retailer.

The deal announced Friday adds prior seasons of TV shows such as "Parks and Recreation," "Parenthood," "Friday Night Lights," "Heroes," "Battlestar Galactica" to its lineup.

About 22,000 movies and TV episodes are now available in its Prime Instant Video service, which is an enticement for people to sign up for the shipping program, Amazon Prime.

The program promises free two-day shipping on a variety of goods for an annual fee, which can cut costs for people who do a lot of shopping on Amazon.com.

NBC is a division of Comcast Corp.'s NBCUniversal.