Yahoo! has released Screen, a video app that brings on-demand content from several providers, including Comedy Central, ABC News, and The Onion, along with video from the web. You can select popular videos or find something to watch on your own, and share videos you like with Facebook, Twitter, and email.
Navigation is fairly simple. Tap the video that is currently playing to bring up the app's controls. Along with playback and volume, there is the channel bar on the left side, from which you can pick the channel you want. Additionally, you can simply search for something to watch by tapping the bar's maginifying glass. Tap the four white sqares on the right of the screen to get an overview of all of the available channels. From this view, you can swipe through videos from each channel and make a selection. While watching a video, you can swipe left or right to watch a different video from that channel, and up or down to move to a new channel.
Yahoo! Screen is a free universal app that is available right now on the App Store.