Gizmodo Reviews RealPlayer SP
"Real's new RealPlayer SP software, currently in beta, adds functionality to rip YouTube and other streaming videos from the Internet and get them onto whatever handheld you choose. It works well enough, but it's also crammed full of unnecessary features. RealPlayer SP is the evolution of the long-running RealPlayer software, which has become a multi-limbed beast of a program: It's a media manager and player, along with a packaged web browser, a subscription and a la carte music store (Rhapsody), a gaming store (Real Arcade), an audio recorder, and now a streaming video ripper/converter with ties-in to social networking sites."
The long and the short of it is that if you're using a device like a Zune or a phone that can play h.264 video, this is a decent way to grab content from YouTube and other social video sites and get it onto your device, with conversion if necessary. It does a lot more than that, but the question is whether or not you need that fucntionality...