I will be walking you through how to open locking DVD cases that have the Green/Red lock symbol on the edge of the case. If you have the kind with the red bar, see this instructable.
Of course, I do not encourage you to use this for illegal purposes. I figured this out due to bringing home DVDs from the library that did not get unlocked.
Step 1: Materials
In order to unlock the DVD case, the least that you can get by with are two very strong magnets. The magnets pictured below are harvested from a hard drive. Generally, the older the drive, the larger and more powerful the magnets. Some new hard drives and some laptop drives have magnets which are too small and weak to use for this purpose.
The other item that can come in handy here is a screwdriver with a small regular tip. You can also use a knife, icepick, etc... as long as it has a tip small and sharp enough to grab the plastic.
Step 2: The Locking Bar
The locking bar is not accessible from the outside of a locked DVD case. It has a magnet on each side and the default position of the magnets keeps the locking bar from moving from the position that it is presently in. This is where the magnets come in handy.
Step 3: Attaching the Magnets
In order to move the locking bar, we need to attach the magnets to the locking bar from the outside of the case. This is fairly easy, as the magnets stick to the case very nicely when you are in the right spots.
1. Take the first magnet and place it in the upper right front corner of the DVD case. You may have to slide the magnet around a bit, but you should definitely feel it stick when you hit the right spot. You may also be able to hear the magnet in the locking bar click as it moves.
3. Take the second magnet and place it in the lower left corner on the back of the case. Again you may have to move it around slightly before you feel it catch,
Step 4: Opening the Lock
If you have strong enough magnets (and a measure of coordination), you can do this without an additional tool. If you move both magnets to the right simultaneously, you should see the lock symbol on the bar move. Sometimes it takes a few tries to get the bar to move this way.
The quick and easy way to do this is to take a small screwdriver (or other tool) and use it to move the locking bar. Again, to the left for locking and to the right for unlocking.
If you have the magnets attached but are unable to move the locking bar, you may not have powerful enough magnets. I went through a couple sets before I found a pair that worked well. Weaker magnets like standard refrigerator magnets are NOT powerful enough to do the trick,