@afre @gadolf - sorry, I overlooked the fact that in the video (by the way, I am the author of it) I was working on layer masks… indeed, in recent versions the grain extract and grain merge blend modes have been disabled for masks, as I saw very little use of it.
By the way, the complex procedure shown in the video is not needed anymore in current versions of photoflow, because the gradient tool has a built-in option for bending the gradient shape. For this, one simply inserts one or more control points in the horizontal or vertical line that is shown when the gradient tool is activated. Dragging the control points up or down (or left-right if the gradient is horizontal) creates a “curved” effect, like this:
