Definately not a standard polychaete bristleworm sk8r. Got plenty of those to be familiar with. There a few tentatcles that come out of the head area when it is fully extended, and then they retract into the head. Can't see exactly how many, yet. The body is smooth, kind of black and bluish stripes, very very thin. For comparison in that video, the largest of the zoa heads is around 1/4 inch in diameter
Is this common of the Eunicids, or this another type of worm?