I was told girl (80% the perinatologist said) and he was right at my 18w level 2.
NT Scans are pretty cool...you can see bones, the spine, heartbeating,etc, which is mindblowing to me, considering the baby is what, like 2" long? Size of a grape or so? Honestly, had I not had one myself, I would have NEVER believed that at 12w they could tell you gender. I had no idea...since I had never had an NT Scan before (where they measure the fold on the back of the neck or something, which is amazing when you think about the size of the baby!!) My u/s was so clear, it reminded me of my 20w u/s from my other kids.
From what the perinatalogist told me, they aren't actually looking between the legs so much, since external genetalia isn't formed or is forming, it's some "nub" thing they look at, like what way it points...up is boy and straight is girl. He told me it looks like a white line.
Here's my 12w5d NT scan showing "gender" as far as I can remember what I was told.
http://img.photobucket.com/albums/10...aby_24num2.jpg
The video I got from my NT Scan is awesome, you clearly see legs kicking and baby moving.
If you get some good pics, you can always post them at in-gender.com board, they live for that stuff LOL. My friend posted for me and like 20 replies said "girl" too (and she hadn't told them what the Dr told me.)