The actual few seconds of video starts at 6:50
My inner-planes mentor ThothHorRa has often told me about these creatures as still living within massive inner caverns of the earth. They are able to surface into our outer world lakes where there are deep crevasses connecting the two waterways of inner and outer earth. This explains how they have a large enough food supply and can multiply (marginally) and raise young, without becoming conspicuous to the surface world.
These “connecting passages” as I understand the gist of it, are somewhat dimensional in nature, so they are in essence “portals.”