[Mike Velte]

I dont see how this could happen!
Are you sure there is no audio? Did you play each clip in WMP? Is Pro’s audio tracked muted?
Pro often wont display a waveform or play the audio if the CFA files are not finished being created.

[Mike Velte]

Create your animation at 30 fps in flash, export as uncompressed QT or Windows AVI with no fields. Also export a Shockwave video file if your targets can play that.
Import into a Pro DV project. The best export option is Window’s Media Video 2.1 Mbps for local playback from a HD and many CD ROMs. Dont fool with a DV version. Make a DVD if you wish.
I think After Effects can do a better job than Flash at creating motion graphics with options like frame blending and motion blur. AE can also export as WMV.