The example that's often used is a YouTube video of your child with music playing in the background, or a slide show that you create with music in the background. If that is non-commercial and you're not making any money from it...and it's being done right now. It's within the ability of everybody who has a computer. It's being done. Consumers are used to it, and they are being creative and non-destructive.
As soon as it turns into a commercially successful remix, if you will, that gets sprung out of the act and you have to compensate.
Those are two fairly simple examples I can give you.