If you believe an user is abusing the policy or violating our Community Guidelines, you can go ahead and report them. Here's our Help Center article which has more info on how you can do that: https://goo.gl/LRuY2d . Hope this helps.
Oh ok! When something is flagged or reported, it’s not automatically taken down. A flag just means we'll review the video and content will only be removed if it violates our Community Guidelines: https://goo.gl/KYov87