Sorry for the lack of acknowledgement of the posting of the video, and I also apologize if this is classified as thread necormacy. I forgot about this from where I've been putting attention towards '06 instead of Heroes, for some variation on what I was playing XP And to finally complete the game, after I've owned it for 3+ months and hadn't passed even Sonic's story...
Anywhos... after watching the video and carrying out more tests, I have deduced that the 'fake wall' does not exist in the X-Box version, or at least the 'X-Box Classics' re-release. I've tried pushing against all areas of the segment of the wall shown in the video, and I have had no success in getting through. I also tried it with Team Sonic again, and I couldn't get them through either ;_; Meh... definitely a version difference, but oh wells... nothing can be done about that, since differences aren't accounted for. Still, thanks for providing the video anyways Marth. Hopefully it helped others out where it wasn't able to for me.
...Though, I can report, as much as the wall may not exist... I have got through to the section the wall leads to. How? Simple. Thanks to James Bertoli's findings with Power Plant, and how the trick with gaining another flight guage mid-flight and boosting up is also used in other places (e.g. Chaotix getting into turtle area in Ocean Palace, and Rose going further in Final Fortress), I tried that in the corners of the walls. At first, I tried on the right side, but didn't get anywhere. However, when I tried it on the left, I gained another flight guage mid-flight. This on its own wasn't enough to help, but very shortly after gaining the first one, I gained another, and was pushed above the ceiling. From there, I just headed forwards until I ran out of flight guage, and dropped in front of the cloaked robot. Guess it shows that almost anything can be overcome using flight XD;; Walls and ceilings are no match for the flight characters! *ahem...*
So, if anyone else is having trouble with using the 'fake wall', give this method a try instead ;) I don't think the specific corner mattered towards the success directly, as normally you don't get an extra flight guage each time, so try any of the corners until you succeed.
And just to prove I've done it, here's a picture I took, with the cloaked robot behind Chaotix:
http://img137.imageshack.us/img137/1769/chaotixinareaafterwallvm4.jpg