About masking device fonts

You can use a movie clip to mask text that is set in a device font. In order for a movie clip mask on a device font to work properly, the user must have Flash Player 6 release 40 or later.

When you use a movie clip to mask text set in a device font, the rectangular bounding box of the mask is used as the masking shape. That is, if you create a nonrectangular movie clip mask for device font text in the Flash authoring environment, the mask that appears in the SWF file will be the shape of the rectangular bounding box of the mask, not the shape of the mask itself.

You can mask device fonts only by using a movie clip as a mask. You cannot mask device fonts by using a mask layer on the Stage.