From what I have read, with Google new private policy, it can collect lots of information about your personal stuff, which include your location, interests, age, sexual orientation, religion, and even health concerns. Then it can use it for its internal purposes.
I was advised to delete your Web History of your Google search and also YouTube viewing history as well.
This is how to Remove YouTube Viewing History:
1. Log in to your Google account.
2. Go to https://www.youtube.com
3. Click your user name and then select "Video Manager" on the top left hand side .
4. Click "History" below.
5. Now click "Clear Viewing History"
6. Click “Pause viewing history."
7. Click "Search History."
8. Click "Clear all search history."
9. Click “Pause search history.”
That's how you remove all your YouTube viewing info from Google.