Trailers are short video clips from a movie. Some online video rental services allow you to watch these trailers over the internet to give you a preview of the movie.
Option to buy
This is simply whether or not the online video rental service sells movies as well as rents them.
Movie ratings
Ability to allow users to give their opinion/review and rating of a movie. Generally, this is in the form of a 1 - 5 star rating. Most online video rental services have this feature.
Movie reviews
Detailed reviews of movies, usually from popular trusted critics.
Family editing
Editing the movie to remove questionable content such as nudity, language, and violence.
Personalized movie recommendations
Personalized movie recommendations allow the user to rate a particular movie that he or she has seen and then get recommendations of additional similar related movies based on how the movie was rated.
Detailed information about the movie
Information such as year released, actors, director, genre, MPAA rating, etc.
> Online DVD Rental 
