Here is how to opt out of the ad tests:
On a computer, go to Netflix.com, and select Account from the pull down menu in the top-right corner. You will find a setting option called Test Participation. There, you will be able to opt out of tests and previews.
For now, as long as Netflix keeps these new promo/ads as a test feature you will no longer see them. If they ever roll them out to everyone the ads will reappear.
*Note you will need to do this for every profile on your Netflix account.
Here is a statement Netflix sent Cord Cutters News on the ad test.
At Netflix, we conduct hundreds of tests every year, so we can better understand what helps members more easily find something great to watch. A couple of years ago, we introduced video previews to the TV experience, because we saw that it significantly cut the time members spend browsing and helped them find something they would enjoy watching even faster. Since then, we have been experimenting even more with video based on personalized recommendations for shows and movies on the service or coming shortly and continue to learn from our members.
In this case, we are testing whether surfacing recommendations between episodes helps members discover stories they will enjoy faster. It is important to note that a member is able to skip a video preview at any time if they are not interested.
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