Something finally annoyed me enough that I've decided to write a 'how to' guide, since I couldn't easily find one elsewhere.
Last night, I bought two DVDs down in Chadstone (about half an hour from the city). When I got home, I noticed the person serving me had not removed the Amaray Red Tag devices from the DVDs. Google revealed that, according to Amaray, I was stuck - I wouldn't be able to remove these devices without their magic tool, so a trip back to Chadstone would be required (to return to the store of purchase). According to the propoganda, I had little chance of removing the device without destroying the DVD.
Fortunately, however, Amaray have underestimated the humble Swiss Army Knife.
After completely destroying the first case (no damage to the paper cover, booklet, DVD or Red Tag - even though this first attempt was by brute force with a screwdriver), I put the resulting Red Tag in an open DVD case and proceeded to play with it until I understood it.
The Amaray device is quite simple - a small, slightly V-shaped metal 'rocker' has one end pushed down by a plastic tab, so the other end sits up and doesn't let the device pull out. By pushing one end of the metal 'rocker' up from underneath, the other end drops down, letting the tab slide out.
A small catch is that you need to gently push the tag in as you push the rocker, as the rocker will otherwise catch on the case edge and not open and slide out.
An important point - no force is required at any point, if you're applying force, you're risking your DVD. This technique is easy if you understand what you're doing.
A small bonus - you get an undamaged Red Tag DVD security device to put into your friends' favourite DVD when you're bored - since the store didn't remove this device, clearly they intended to sell it with the DVD.
Here's the technique I used on the second DVD case, in full:
I expect it would take little practise for someone with all the wrong motivations to work on a technique to stab a swiss army knife through the back of a DVD cover and remove the security tag in store - I'm unsure if this could be done reliably without damaging the paper cover (ie. with just a small slit in the plastic cover), but I am confident it could be done discreetly and successfully.
Anyway, I hope this guide helps anyone else in the same situation, and points out to others how little real "security" this device provides - sure, it has only cost me a couple of dollars in new DVD cases, but the delay of ten minutes before watching a DVD I had just purchased was quite annoying! (And the DVD was Rowan Atkinson Live, which I hadn't seen in years and wasn't going to wait until the weekend to return to the store before viewing it!)