We talk about this a good bit in the next episode, which is now up.

There are a number of situations when you'll want to bind to the service container.

If the instantiation of a class requires a number of dependencies (each with their own sets of dependencies), it can become tedious to construct. Though you could create a factory class for this, it's often easier to throw it in the service container for easy retrieval.
Often, a class will require a number of parameters that might be defined in your configuration directory. If we bind to the service container, we have a single point of entry to read the necessary configuration and build the object.
Automatic resolution. This means Laravel will do its best to automatically build up the object we request - without requiring any effort on your part. It'll use PHP's reflection API to read the dependency graph for the class you request, and automatically instantiate what's needed. This is incredibly convenient.

Service Container Fundamentals