Several related posts around here somewhere, but I believe that the essence is that Moho doesn't export image effects, or image layers that are skewed/scaled/translated in 3d space, or manipulated with bones. As a format, for the most part, Flash just doesn't have the direct ability to display some of the things Moho can put out. At least certainly with a file size that would be of any use on the 'net. And some bits flash goes "huh?". I wouldn't at all mind a direct output to Flash video as an option, but that's doable now as a simple conversion from one of the available export formats. So my simple statement should be, no bug. Just limitations in the Flash format as it relates to what Moho does.
No, not a bug. SWF, being vector-based, does not allow for these kinds of pixel-level effects. SWF is actually quite limited in what it can visually express.
If you look in the Moho manual, under Reference->Flash Tips, you find more information about what can and what can't be exported to Flash.
