Well, if you are referring to the picture, yes, it is Acer palmatum Waterfall (I know...it's mine!)

As far as getting this exact cultivar, it needs to be grafted in order for it to have the exact same characteristics. You can plant the seeds & see what comes up, but they will all be a little different. In my mind, I think it would be exciting since this is how new cultivars are introduced.

Good Luck.

Yes it is a A.P. Waterfall. I have one as well and looks exactly like it - Beautiful! Just as lalalandz said above you need to have a grafted tree to have it be called a "true" A.P. Waterfall. The only other way to do this is to try to take a few cuttings from the tree you have and try to root those cuttings by using a rooting hormone.(It's something you can find at Homedepot or your local garden shop for under $10) This however is very difficult and don't be suprised if you take 10 cuttings and all 10 die.

Grafting is not as difficult, but you need to find an understock to graft your cuttings on. It has to be an Acer Palmatum Green leaf or red. You usually have to buy these in bulk, 25 or more at one purchase. Do a search on google for Japanese Maple Rootstock.

Hope this helps!

You can grow your own seedling rootstocks. But, the investment is an extra year of work. The green-leafed rootstocks are more vigorous than the red. If possible, I'd go for those. And, doing the bud graft is more successful than cuttings.