Yep what you said. Great advice. I got into reefing back in the early 90's and these were relatively cheap back then. I used to get them from a wholesaler for $10 a pound and sometimes $8 depending on how many worms and life on them.I have kept them a few times over the years. Host coral is usually porities, but it is sometimes cyphastrea (the one in the video). Neither coral is particularly difficult to keep as long as your system is SPS friendly. The fan worms do need fine particulate foods. If you have fan worms thriving in your system already, then you are probably already good. Most systems with a decent fish population would 'qualify'. If not, some regular addition of foods will be required. The bigger problem, particularly with the aforementioned fish, is that the frilly worm heads are irresistible to angels and even some tangs. The worms will shed the head if it is sufficiently irritated. That won't immediately kill the worm. but if it happens repeatedly the worm will starve and die. The worms also don't like a ton of flow.
I am not able to keep them in my main display, but they do very well in my frag tank. I have one there that is almost 5 years old and both the coral and worms continue to thrive. Tank in the video looks pretty new, so that's potntially a problem. You'll need to be adding fine particulate foods.