What does the metric « Time to initial play » mean?

When a visitor opens a page with media content, the time of the page load is recorded. When the visitor plays the media, Media Analytics calculates the number of seconds that have passed since the page load. This difference is referred to as the « Time to initial play ». For instance, if a visitor loads the webpage at « 12:25:35 » and begins playing the video at « 12:25:41 », the time to initial play is 6 seconds.