Themo, I tried using your border-less portal tile in one of my maps. It looks off, I have to say. It's not taking up the entiriety of the grid space.
I think when he made the "borderless" Portals, he simply erased the border without resizing. That means that they only work as intended when used as single portals, you can't use several as a connected portal together. For single portals, they should work when you place them on an autotile-floor as they are in slot D in your configuration. But I don't think there is a simple solution to use them resized, because they're higher than wide and any graphical resize will distort their picture.
Thanks! I had been trying to make my own tree wall thing but now I have a decent replacement. Don't worry, I'll credit you.
Does anyone have these animated portals still? If so, could they please repost them? The original post's images are all broken (lead to "file not found" on ImageShack) and not only would I love to use these myself, but feel it's a shame if they were no longer available for others to use just because the links expired. EDIT: Thanks to another kind poster (thanks!), Themo's portal tiles are now available again in this thread: *HERE* I hope these are useful to other people as well!