I've been trying to get into modding for FNV, but most of the tutorials on youtube seem to end rather quickly with only 1 or 2 videos. Should I just use the KDS videos, even though they're on FO3?

While there are a few differences between the two games, they're essentially the same when it comes to modding. So learning from one game will give you skills towards another. While New Vegas has a few extra things you can work with, all the stuff that Fallout 3 also uses in the GECK are virtually identical in both versions. Any changes that do occur you should have no trouble figuring out on your own.

PS: Oh wait, are you referring to just adding mods to your game or making your own in the GECK? If you're just adding mods, then the two games are even more identical.