The security exception message is standard for sites that offer https access but haven't done whatever needs to be done to certify the validity of the site. I doubt TER wants to officially register itself but at least we can use SSL for our own security. Remember, passwords typed on http sites (without the "s") can be intercepted and stolen. HTTPS encrypts all communication between your computer and TER so your password is secure and whatever you're typing can't be read by prying eyes.

I've been using https here for a long time. There's no security threat that I'm aware of and I feel safer knowing my typing is encrypted.