At first I thought it was an anemone of some kind, since they spawn very similarly to the way that "creature" did. But them I saw the video you linked. Closer look showed no tentacles, so no anemone. I think it's likely a case of some up-and-coming (or even somewhat well-known) SFX guy/company creating a little video to showcase their work, in hopes it would go viral.
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While it seems like most of you are allergic to the "like" button, I just want to personally say thanks for looking anyway.