Scroll depth tracking in web analytics is one of those things you simply must do, especially if you have a content-heavy site. Tracking scroll depth not only gives you an indication of how much users are digesting your content, but it also lets you turn meaningless metrics such as Bounce Rate into something far more useful. If you've already been tracking scroll depth in Google Tag Manager, you've probably been using either Rob Flaherty's brilliant Scroll Depth jQuery plugin, or Bounteous’ equally ingenious Scroll Tracking recipe.
Last updated 20 April 2020: Clarified how lazy-loaded videos can be tracked with this trigger. Let's cut straight to the chase. Google Tag Manager has just released the YouTube Video trigger, which gives you native support for YouTube video tracking. And it's great! Even though we've been more than satisfied with the excellent tracking scripts provided by e.g. Cardinal Path and Bounteous (with a small modification from yours truly), this is a no-brainer for native support in Google Tag Manager.
The beauty of #GTMTips, at least how I've envisioned them, is that they can be really simple or crazy complex. The important thing is that the idea is conveyed clearly enough. That's why so many of these tips have originated from discussions in our Google Tag Manager Google+ community, the Product Forums, and in private email correspondence with people asking for help. Today's tip, for example, originated from a back-and-forth with Süleyman Okan, so thank you for the inspiration!