The number of seconds the player was in this state. If this is the last
entry in the list, the player is still in this state, so the duration
will continue to increase.
state
string
The state the player entered. This could be 'buffering', 'playing',
'paused', or 'ended'.
timestamp
number
The timestamp the state was entered, in seconds since 1970 (i.e.
Date.now() / 1000).