"Today, we're excited to talk about proposed extensions to HTML5 video that enable playback of premium video content on the web. We currently use Microsoft Silverlight to deliver streaming video to web browsers on the PC and Mac. It provides a high-quality streaming experience and lets us easily experiment with improvements to our adaptive streaming algorithms. But since Microsoft announced the end of life of Silverlight 5 in 2021, we need to find a replacement some time within the next 8 years. We'd like to share some progress we've made towards our goal of moving to HTML5 video."