I think that the nuns in this video are the same ones mentioned in this article from LifeSiteNews.com. Here is a quote from the article:
The angelic voices of a new order of young nuns has taken the world by storm, surpassing Rod Stewart, Taylor Swift, and One Direction in sales last week at major retail outlets such as Amazon and Barnes&Noble.
If I am not mistaken, I believe I have received a couple of other chant CDs from these nuns for free in the mail, but it appears that they are reaching a wider audience with this new Advent CD. This appears to be the link to the CD on Amazon.com. The CD is currently ranked #63 on Amazon's bestsellers in the "Music" category. Very impressive!