First, make sure you have created your Free Jazzedge Account.
After you login, you can fully browse the site and view all courses, lessons and chapter pages. However, you will not be able to download any of the resources (sheet music, backing tracks etc.) or view many of the videos.
The videos that you can view will have a STAR next to them like this:
Any lesson chapter with a STAR beside it you can watch as long as you are logged in.