Hi lightspeed, I played a lot with Audacity when I was making stereo Haptek skits with two characters (and of course, lipsync by PeoplePutty). Maybe you could try the following method (I give it for free, lol). Of course it can't work "live" but, because you show YouTube videos, it would be fun to do.
1. You record voice and music on two different tracks. If you use plugged instruments, it's perfect, no interference between voice and music. With unplugged instruments, you could record the music track before, and then sing with headphones and record the voice.
2. You put the voice track in PP and get an ogg with a perfect lipsync.
3. You play your Haptek stuff with the voice only and make your movie as usual.
4. You add the music track to the video. Of course the best of the best is a stereo music with a mono voice, all is possible with Audacity.
I always wanted to try that but now it's too late. And unfortunately I don't sing and don't play any instrument.[

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