The alternate color scheme shown at 2:30 is from Shinkawa's concept art for MGS1! It'll be one of the first results in an image search for REX concept art - only really notable difference from the final design being the railgun, which had a round cannon type of look. Mentioned it in previous reviews but the upper left section of the waterslide sheet is invaluable lol. The caution markings (and particularly the name of the mech across the top of the head) are visible in MGS4, making em a canonical part of the design... but these waterslides are included ONLY in the Black Ver kit. If you're ever planning a fully painted, game accurate look for MGS4 Ver REX, I'd recommend donating those waterslides to that build, don't use em on the non-canonical Black Ver. :D
I (mostly) build the non-black version for my channel for a kitbash vid and had a blast. Some great mechanics in there, lots of details. I painted mine black so I was kinda salty when a black version ended up being released anyways lol.
My reason for calling it bland during the stream was, that most of the details are almost invisible, whilst the grey kit does show them. Hmmm, not sure if the stock kit shows the digital camo as a suggestion, but interesting none the less.
I just got my hands on the original release of this kit. Too bad it doesn't come with waterslide decals like the black version does. Also wish someone produced a detail up set or photo etch detail for this kit.