You don't have to register to watch anything on channel5.com.
But you can comment more easily and sign up to receive information about upcoming shows by email if you register with channel5.com.
Commenting on episodes or web pages is quicker if you are registered and logged in.
Commenting when logged in means you can add your comment directly:
But if you're not logged in, you have to provide more information before submitting your comment:

Register with channel5.com here.