YouTube videos are so incredibly powerful that every artist and band has to do them in order to both engage their current fan base and also to expand it as well. That said, many artists shoot randomly and never think of the consequences of not getting releases from people and places in the video.
There are times that people and venues want money for using their name and likeness. That used to require a reshoot, which wasn't always possible, until now. YouTube now gives you the tools to selectively blur any part of your video for maximum anonymity.
Way back in 2012 YouTube launched a face blurring tool, but the current update allows other things to be blurred out in the video like license plates, phone numbers, wardrobe malfunctions, disturbing imagery, etc.
You draw a box on top of the part of the video that you wish to blur, and then the feature will track the object as it moves throughout the video. You can also choose when the blurring begins and ends.
This update is only available on the desktop version of YouTube at the moment, but they promise that the mobile version update will follow soon.
Here's a video that shows how to do it.