The HowTo and the tutorial talk about temporary usernames starting with
=. Here's how it works. When you connect to termcast.org for the first time with a username starting with
= and some SSH public key, the server permits the access and associates the SSH key with the username provided. The server will then remember the username and the key for the duration of your termcasting session. This means that nobody can connect to termcast.org during that time and hijack your session (unless they know your SSH secret key). After you disconnect from termcast.org, the server will still remember the username and the key for 5 more minutes. Then it will forget it all, and the username becomes available for grab by anyone interested. That's why it's called temporary.
If you want a permanent username, you need to Regsiter. After signing in, you can use Settings link from the user menu in the upper right corner to upload your SSH key. Then your SSH key will be permanently associated with your username.
You can then use your permanent username for SSH connections to termcast.org, without
You get your own profile page on termcast.org, with all your live and recorded sessions. All your session recorded using your permanent username, or uploaded via site interface while logged in on site, will be assigned to your account.