If you read back, you'll see that I also mentioned McTube. McTube acts as if it is a music player and music players can continue to play music in the background. McTube isn't playing a video with sound, no they are taking the sound of a video and play that sound.
That's not entirely true. Apple specifically says that both audio and video can be played in the background. iOS has no problems with video in the background - in fact, if you're using AirPlay that video will continue playing on your TV even after backgrounding the app (assuming the app makes use of background capabilities.) You might be thinking of videos played from websites via Safari. As far as I can tell, Safari makes no attempt to continue audio/video playback when backgrounded.
Google, if they wanted, could make a simple change to the iOS YouTube app which would allow it to continue playing even when backgrounded.
http://developer.apple.com/library/...cationsFlow/ManagingYourApplicationsFlow.html
Playing Background Audio
An app that plays audio continuously (even while the app is running in the background) can register as a background audio app by including the UIBackgroundModes key (with the value audio) in its Info.plist file. Apps that include this key must play audible content to the user while in the background.
Typical examples of background audio apps include:
Music player apps
Apps that support audio or video playback over AirPlay
VoIP apps
When the UIBackgroundModes key contains the audio value, the systems media frameworks automatically prevent the corresponding app from being suspended when it moves to the background. As long as it is playing audio or video content, the app continues to run in the background. However, if the app stops playing the audio or video, the system suspends it.