Okay, so I took my Beetle to the dealer to have them replace the bulb, and I asked them to let me watch the mechanic as he replaced the bulb, which they did. He showed me how to do it, and the first thing that I noticed was that you DON'T turn the 5mm nut 1/4 turn, you turn it until it stops turning. That's why I wasn't able to get the headlight assembly out of the car. He even let me turn the nut with his ratchet, to see where it stopped turning.
Something you don't explain is that, on the driver's side light, once you've turned the nut 1/4 turn, and as you are pushing down on the lever, how do you get the headlight assembly out? There is nothing to grab hold of from the front of the headlight, and you can't get your hands on the back of the assembly, so how do you get it out? I tried putting the handle of a pipe wrench between the back of the headlight assembly and the air filter housing and pushing as hard as I could while pushing down on the lever, and the headlight assembly wouldn't come out. After an hour, I gave up and took it to the dealer.....a 15 minute job my rear end!