The self-contained YouTube app is far better to me. However, I get tired of Safari links automatically taking me out of Safari and into an app (YouTube, Amazon, eBay, etc.). There needs to be some sort of simple method to prevent this... I'd rather have an optional, translucent button that allows me an easy option to leave Safari for the app, instead of jumping through hoops to open a YouTube link in Safari. Sometimes I search for an item on Amazon, and I'm yanked out of Safari into the app. Then I search for a YouTube review and am yanked out of Safari again. Maybe I want a safari tab with Amazon items and a tab with YouTube vids without double-clicking the home button to multi-task, when everything I need is already right there?
I do agree YouTube needs a background feature. A mixed bag, but overall a better app in my opinion.