The length of the video.

The tag value is an ISO 8601 duration in the format PT#M#S, in which the letters PT indicate that the value specifies a period of time, and the letters M and S refer to length in minutes and seconds, respectively. The

characters preceding the M and S letters are both integers that specify

the number of minutes (or seconds) of the video. For example, a value of PT15M51S indicates that the video is 15 minutes and 51 seconds long.