I saw your video just now.
You missed 3 secret rooms.
Plum duff area: Check 10:15 & 12:12 (2 rooms)
Nitta's Blessed area: Check 30:35 (1 room)
you didn't enter the latter half of Nitta's area.
Jump at 32:32 .
(You can see my promotion video uploaded on Dec 4.)
There are no problems in other areas.
You would be able to collect ALL 200 items !!
If you don't want to waste your time,
you can see the map via map editor.
Press F2 at the menu screen,then press Return.
up: 8 key
down: 2 key
left: 4 key
right: 6 key
return to the menu: Esc(2 times)
PS. There's nothing beyond that place in Lemmings area.
As you know, original Lemmings game has such "no points" places sometimes.
I like those maps, so I inspired them.