SWF as a DRM measure doesn't work terribly well -- it is easy to carve the data out of the SWF file. The JFIF headers (and equivalent for PNG and GIF) stick out like a sore thumb to forensic file carvers.

Even encoding or encrypting the data to be decoded by the flash player doesn't achieve strong protection -- the same carvers can be applied to process memory with similar ease. If you are going to display content on in an untrusted (end-user) process, content producers are going to have to accept that they can save that content.