It is not entirely true that you cannot embed swfs within a Flex publication. You can but there are problems.
The Swf must be imported as a video. It can stream the swf from your server on the net somewhere so it does not have to be embedded within the publication and when you launch your Flex publication on the web, this publication will then stream your video.
BUT and it is a big but, all interactivity is lost until the video has completely streamed (note streamed and not played). If you have a fast connection, then perhaps the video will stream quite quickly ie. it will download the video while it is playing, and will download quite a while before it has finished playing. So interactivity can be reacquired before the video has stopped.
When I say interactivity, I mean you can press a button and your Flex publication will respond.
I have used video in Flex publications and have managed to work around the problem by getting the video to stream completely at the beginning of the publication and then use the same video in more interactive pages. You can see two examples here.
http://david.moxon.free.fr/troy.html
http://david.moxon.free.fr/temp/gaulle.htm
I teach English so obviously the video is not used for the same purpose as a promotional video for a band, but it might give you an idea for a workaround.