This is part 20 of my 100% Super Mario 3D World Walkthrough.
This part includes World 8-Train "The Bowser Express", World 8-4 "Footlight Lane" and World 8-5 "Deepwater Dungeon".
Below are the times when I get the stamp and green stars in each level.

00:52 - World 8-Train - The Bowser Express
01:10 - Green Star #1
01:55 - Green Star #2
02:11 - The Bowser Express Stamp Location
02:20 - Green Star #3
04:20 - World 8-4 - Footlight Lane
04:57 - Green Star #1
05:24 - Green Star #2
05:57 - Footlight Lane Stamp Location
06:18 - Green Star #3
08:18 - World 8-5 - Deepwater Dungeon
08:55 - Deepwater Dungeon Stamp Location
09:49 - Green Star #1
10:34 - Green Star #2
11:15 - Green Star #3