I compared the clip to the original stream and this does appear to be an intentionally misleading edit. The clipper removed several sentences that made it obvious she was talking about the cube. The rest of Marine's segment of the clip is basically unedited, and starts
here in the original stream.
I watched the original stream before the clip came out, and Marine unequivocally stated that Kumarine was being filmed on Sunday evening for a video to be released later, and anyone who had been there at the time could have ended up in the video. As she was saying this, a large portion of the Japanese stream chat took this to mean that she might have been in the costume herself, which can be seen in the comments. Someone also mentioned this to Korone later, which is covered in the first segment of the clip.
It looks like the clipper ran with this possible interpretation and did some intentionally misleading editing to further support the theory. (The clip got 150k views in 12 hours, so it worked out well for him.)