'Play for a set time'
This lets you specify the amount of time a play list item is displayed before moving onto the next item. For example, you may be using play list items with a picture control to show images every 10 seconds. You can specify the amount of time this item runs for. If you put a tick in the 'Use default play duration' tick box, then this takes the amount of time from the Play list tab on the Properties form instead.
AUDIO AND VIDEO CONTROLS
'Play until finished'
Audio and video files have running time. For example, a
audio MP3 file may have a running time of 3 minutes 5 seconds. Play until
finished will play the audio or video file for it's complete running time,
before moving onto the next play list item.
'Specify part of the video' or 'Specify part of the audio file'
This is for audio or video files. If an audio MP3 file may
have a running time of 3 minutes 5 seconds, you may just want part of this, for
example a chorus. You can set the play from 1 minute 30 second to 2
minutes 35 second for example, so that you are only playing a 35 second section
of the song.