This is the best youtube viewer/downloader IMO.
I have tried them all, this has the most features, it's minimal, and has many nice features.
You have access to you're channel, favorites and subscriptions. This alone is great, and not available on similar apps I have paid 5x the price for.
You also have an extension for when viewing any YouTube links in Safari, they are instantly captured and auto play in the app.
The app runs in the full window, unlike other apps that have the video and a sidebar or something open at the same time and no way to disable.
And lastly, if you donate to him, I donated the minimum of 2-3 bucks I think it was, the app will download and convert the videos for you. And it does these two things very well, fast downloads and lots of video settings.
The only thing I noticed bug wise, was when seeking with the nav bar on the bottom, sometimes, the bar will jump out of place and stay in the middle of the screen until you close the app. And also comments under video option does not work for me.
Don't know why this app get mediocre rating...it's a beta, and the guy is asking for a measly 2 bucks for his download and converting features.
I'm loving this app, I use it daily, and I look forward to the updates.