YouTube is experimenting with preventing users from using ad blockers. In what has quickly become known as the "Three Strikes" warning, viewers have reported seeing pop-up messages when browsing the site using ad blockers.

Several screenshots have appeared on Reddit and Twitter, with the warning explaining that YouTube's "video player will block after three videos" unless you disable your ad blocker or sign up for YouTube Premium .

The warning continues: "You appear to be using an ad blocker; playback of the video will be blocked unless YouTube is on your allow list or your ad blocker is disabled. Thanks to ads, YouTube is free to billions of users around the world; with YouTube Premium, it is ad-free and creators get paid from their subscriptions."

The Google-owned company confirmed that it is conducting an experiment and reinforced that if viewers "ignore repeated requests to allow ads on YouTube,"

their viewing will be terminated.

A YouTube statement provided to Tom's Guide explains: "We are conducting a small-scale experiment globally to encourage viewers with ad blockers enabled to allow ads on YouTube or try YouTube Premium. Ad blocker detection is not new, and other publishers regularly ask viewers to disable their ad blockers.

YouTube has not disclosed how many users have received this notification or in which countries it is conducting this trial. It is also unclear if or how viewers can re-access the site after their viewing has been blocked.

YouTube is understandably concerned about turning its attention to advertising; the majority of YouTube's revenue comes from advertising, which has been declining for the last three quarters. This is a fairly significant reason why the platform is taking a more aggressive stance.

This approach is not new, nor is it unique to YouTube. Although its revenue model is different, Netflix is currently in the process of trying to crack down on password sharing as a means of increasing subscribers. Some evidence suggests that it is working.

According to the latest figures, YouTube Premium, which does not include ads and allows users to download videos for offline viewing, currently has about 80 million subscribers worldwide.

Therefore, while YouTube's ad blocker blocking test is a limited experiment at this time, it would not be surprising if the test is successfully expanded worldwide.