Google added a six-second autoplay preview on video search results from the Google App and Chrome on Android devices.
This change allows users to have access to see a video preview directly in search results, giving them a better idea of what they’re about to watch before they click through. Video results often appear legitimate with the initial thumbnail, but when you watch the video you realize it was a poor result.
Currently, by default, the previews only play when your device is connected to wifi, but on mobile networks, you can enable the preview or opt out of the feature. This can be done in the Google App or Settings for Android Chrome.
Google uses an algorithm to choose which six seconds to show. Currently, marketers do not need to provide any type of markup in order for the previews to appear in search.