Yahoo Web Search

If there's a Content ID claim on your video, you cannot mark your video with the Creative Commons licence. By marking your original video with a Creative Commons licence, you're granting the entire YouTube community the right to reuse and edit that video. What's eligible for a Creative Commons licence?

If you allow Creative Commons people can chop up your videos however they like. It would seem that they only users who will be willing to allow Creative Commons are common YouTube users, those who utilize the site for fun opposed to business. Potentially some small businesses who are greater risk takers may also entertain this idea.

you can earn adsense from creative commons videos and you can earn from pre-roll and post roll ads that you place yourself as long as you don't edit the video itself. It really depends on the license of the video though, as most creative commons license is for non-commercial use.