Best Way Of Overlaying Lyrics On Live Singer & Audience Video Feeds

[clickclubz]

A lot of people who come to my shows want to see the lyrics of the CD+Gs or other Midi Karaoke tracks on top of a live video of the singer and/or audience. Is there any software for this? Do I need to use a video mixer (if so what is the cheapest effective mixer in the market)? Can I connect it to my laptop on which I run the karaoke software using perhaps a digicam and firewire interface? Anyone is successfully using what I am asking, please tell me how you do it.