RightBooth version 7.3.19 has just been released. It allows you to add video backgrounds to your karaoke video recordings (and your standard video recordings). Here's a small section of a karaoke video I received from a RightBooth user.
It was created using the karaoke recording feature and the real-time green screen video background replacement feature.
It was recorded at 720p, 30fps using a Logitech C920 and it just shows what you can achieve when you have the right equipment, the right lighting and the right software...
And here is a photo showing the actual green screen background set up that was used for the karaoke video recording: