Glad it worked, but I think it only worked because your key is broke off in the lock cylinder, allowing it to turn from the back side. Reason I say that, is because I initially thought that would work, until I went out in the shop and tried to verify it. Many times, we've all opened the latch from the outside with a screwdriver when the lock cylinder is out, like when we're doing body work/painting and need to open/close the trunk for alignment. Only problem was when I tried it from the back side, it wouldn't turn without inserting the key in the cylinder. (I was working with about 2 hours sleep when I initially typed a reply to you a couple of days ago, but changed it to removing the latch bolts after verifying it didn't work)
If you notice in the video, it looks like the lock cylinder is already removed from the trunk lid when he uses the screwdriver. It also looks like that retainer spring was broken from the cylinder which maybe didn't keep that drive pin in place when turning the key, letting the latch work from the back. He verified it when he said the key just went in and flopped from side to side and nothing happened to unlock it.
Basically, I'm just putting this out there that it will not work for someone if their lock cylinder is fully intact, and you just lost your keys. Good news is, once you get that cylinder out, your locksmith may find a key in there when you bring it to him to match the doors. ( I also verified this in my '69 Z/28, it won't turn without the key inserted).