If your PSN account is registered in the USA, then those apps are in the APPS section of the Vita Playstation Store (and the Vita apps section of the PS3 Playstation Store). If your PSN account is registered in another country, then those Apps may not be available in that country, so you can't download them with your PSN account. Nothing can be done about that, except to create another PSN account registered for a country where the apps are available; and restoring your Vita to use the new PSN account.
I just looked in the Playstation Store on my Vita before I posted the first time. Both apps were there. Everyone with a US PSN account is accessing the same Vita Playstation Store. What do you mean by "it didn't work"? By the way, where you live does not matter. It is the country that you entered when you created your PSN account that determines what Playstation Store you use. The Playstation Store app doesn't know, or care, where you are.
There is no conceivable explanation for why they are in the Playstation Store on my Vita, and not there on yours. Either you are looking in the wrong place, or your account isn't a US account. You said that the latter isn't the case, so it must be the former. The Vita Playstation Store has three main categories: Games, Video, and Playstation Mobile. The Vita apps are in the Games category. The apps are in their own section, labeled Apps. It is second from the bottom. You have to scroll down to it. The apps are in alphabetical order, so Skype and Youtube are towards the bottom of the list. Again, you have to scroll down to them.
Open the Settings app, and then open the Playstation Network/Account Information screen. That will tell you what country your Playstation Network account is registered for. There is one other possibility that I forgot about. If you are using a PSN sub-account, and parental controls are set, then the Playstation Store will hide any games or apps that are not age-rated, or are rated higher than your parental controls limit.