seekToMediaItemThenAt
Seeks to a specific media item and then sets the playback position within that item.
This method first calls seekToMediaItem(index) to switch to the media item at the provided index. Then, it calls seekTo(milliseconds) to set the playback position within that media item to the specified time in milliseconds.
Parameters
index
The index of the media item to seek to.
milliseconds
The target position within the media item in milliseconds.