The SMART Playback settings are located under Playback Options:
To activate either option, simply check the box and then click Save:
Pause on lost scroll - This will pause the video whenever a viewer scrolls up or down and away from the video so the video is no longer in view. When that happens, the video pauses. The video will resume when the viewer scrolls back and video is in view.
Pause on lost focus - This will pause the video when the viewer switches to another tab or another window and the video is no longer in view because of that. When the viewer switches back to the tab with the video the video will resume.