I wouldn't call this harlequin because all the images of harlequin I've seen are multicolored all over. It is a diamond pattern of various colors, like the costume of Harlequin the Commedia dell'Arte character. If you look up "harlequin opal images" you will see multicolored diamonds all over the surface of the stone. What I see in your video is a stone that is green flash on the left side and part of the middle and right, with a few flashes of red and blue on the left. I'd tend to call this a broad flash opal in greens and blues. The lack of reds and oranges does lower the value, as reds and oranges are rarer than greens and blues. The questions would be how thick are the fire layers in the stone. While fire tends to be similar throughout the fire layers, it's quite possible that other layers might have more of the other colors than the predominant green you see on most of this stone. It does appear to be a fairly large stone, so you possibly could cut areas out of it, such as at the top right as we see it, where there is as much red and blue as green.
Another issue with opal that is cut is the viewing angle of the fire. From what I can see, these broad flashes come on for several degrees of view and then switch off. This is why pinpoint fire and broken up flashes of color are generally more valuable, since the stone tends to show color from all angles rather than just from one angle. The cut on this stone is parallel to the layers of fire. This is common because it usually produces the largest stone. Layers are often rather thin. Fire when cut across the layers is usually better...better broken up and more sparkley from more angles. The problem is often that the fire layer is rather thin, limiting the size of a 100% fire stone. I'm not an opal expert, but this is what I can tell you from my experience examining and cutting opal. It is a dark body color, which ups the value considerably over white opal.
I can tell you that from the video that I would like to see the underside of the specimen. It looks like someone cut a flat at right angles to the face you show and that is probably what I would have done, to see what the layers look like. You could cut round sections of this log and there might be different fire in other spots...or not. Or you could cut parallel to the long axis of the log and likely your fire layers would look like the bottom surface...but possibly not> That's what makes opal so challenging. That said, I have not seen a lot of opal logs, so someone familiar with them would know more about what the fire layers usually look like.
It's a nice piece however you slice it (pun intended!). If you do cut it up I'd be interested in seeing what you end up with.