Jihadi social media activists supporting both ISIS and Al Qaeda have been taking advantage of YouTube's privacy settings to upload videos that are only viewable to those who have the direct link to them, but that cannot be found using YouTube's search tool and are not listed under the public profiles of the accounts hosting them. This can be done by changing the privacy setting of the video to "Unlisted."
Below are screenshots from YouTube's Support page describing how to manage the privacy settings of a video:
One example of this method could be seen on August 4, 2015, when the jihadi-affiliated Twitter account @AALMOJA3 tweeted a link to a YouTube video in which a jihadi sheikh commented on the decision by the French satirical magazine Charlie Hebdo to stop publishing images of the Prophet Muhammad. While the video was eventually removed by YouTube, while it was still active, it could be viewed by clicking the link in the tweet as seen below:
However, when visiting the YouTube account's profile page, no videos were visible under wither the "Home" or "Videos" tabs because their status was set to "Unlisted":