The box says: "You can find the password for the next level on this page, but rightclicking has been blocked!"
The right clicking is only blocked on the white box. Just right click elsewhere and choose "Inspect page source". You could have also used a shortcut (CTRL+MAJ+I, depends on the web browser). Here is what you will see:
<!−−The password for natas2 is ZluruAthQk7Q2MqmDeTiUij2ZvWy2mBi −−>