The mayhem surrounding joost invites reminds me of the demand for gmail access.
There are a couple of ways. One is to sign up for the closed beta and wait for the Joost team to release some invitations. A quicker way is to either to seek a friend that already received an invitation. Some users get invite codes to pass along to friends.
Someone has even set up a site for people to swap valuable stuff for invites to the beta video service.
There are also some good advice in this post from MyJoost blog.
In my case, I just signed up and waited. My first impressions are that picture quality and stream speed are good but content is still very lacking. When more shows are available the service will be just great.