The quickest and easiest way to make YouTube kid-friendly is to enable Safety Mode. Safety Mode will screen out potentially objectionable content, so children can view YouTube in a web browser without unsavory videos and vulgar comments floating to the top. You can turn on Safety Mode by scrolling to the bottom of any YouTube page and clicking the drop-down menu in the "Safety" section. If you are logged into your YouTube account, you can lock this feature so it is always enabled. If you have multiple browsers, you have to open each browser and repeat this process to make sure Safety Mode is turned on in each one.
YouTube warns parents that this feature is not 100 percent foolproof, and some objectionable content could seep through its filters. If you want an extra layer of security, you can install third-party filtering tools like Safe Eyes from McAfee or Net Nanny. These services cost money, but they filter all the websites that your children visit, not just YouTube. There are browser-based extensions like FoxFilter for FireFox or Blocksi for Chrome that also filter website content. If you use Safari, parents can use the built-in filtering feature that is enabled when you turn on parental controls in OS X.
Parents looking for a house-wide filtering solution that works with all devices should look at OpenDNS and its parental control service. OpenDNS routes all your internet traffic through its server and filters that traffic for adult content, social networking sites, video sharing sites and more. You have control over the categories of content that they want to block.