Recently Digiarty has released a new version of MacX Youtube Downloader that is compatible with Mac OS X Mavericks. This apps is really great in doing it's job and it comes in FREE! There is also paid version available but for downloading only Youtube video, the free version is more than enough.
MacX Youtube Downloader is capable of downloading 1080p video from video even if it is a protected streaming video (RMTP/RMTPE) such as VEVO. The download speed also quite impressive and there's no reason for not having this apps.
To download this apps, go to the developer's website here.