Unfortunately, that's the only way. And, furthermore, the
audio has to be exactly the same length as the imported FLV. If the
audio is longer, the slide will stop when the audio time has
passed. If the FLV is longer, the video will cut off when the audio
sends. If you are experiencing a pause at the end of the slide,
I'll bet the audio is a bit too short (even a fraction of a second
will do it).
The only way I've found to make this work is to
1. extract the audio from the original video file (I use mp3
extractor pro, a free program from GeoVId.com).
2. Then convert the video to FLV.
3. Add the FLV, and import the extracted audio. They will be
the same length.
I hope this helps. We'll have to wait for Adobe to update
this feature to really solve the problem. :-S