The powers that be at Netflix heard our prayers. As of today, we can now opt out of autoplay previews, a feature of Netflix's user experience that I almost always do not want. Which means: no more browsing shows on your homepage and accidentally lingering on one for too long only to be launched into a trailer that you did not ask for.
Here's how to disable this setting: Sign into your Netflix account on your web browser, select Manage Profiles in the top-right corner, and choose whichever profile you'd like to make the update for. From here, you can deselect "Autoplay previews while browsing on all devices." You also have the option to deselect "Autoplay next episode in a series on all devices" if you don't want Netflix to keep serving you new episodes once you complete them. Then hit save, and voila — no more unsolicited video clips. The preference will be reflected across all of your Netflix devices, though Netflix's site says there may be a delay before it takes effect.