Welcome to the forums.
The file may be corrupt or was incorrectly created to begin with.
It is not worth your time and effort to try to force it to work.
Convert the file to a DV AVI file which you know will definitely work.
You might also want to give Moyea's FLV Importer a try. Their site was down when I tried, but I was just on it a few days ago. Give them time to get their server back up. Now, if the FLV is corrupt (though it seems to play fine), there might be issues. Also, there is a great deal of difference between playing an AV file, and editing that same file.
For conversions, I've had success with FLV to AVI.
Thanks for the welcome and the advice.
Thanks for the advice - I'll give it a try!
Good luck, and let us know how it works. The site is now up, so you can take a good long look.
I had actually bought the plug-in and never got around to testing it. I forgot about it, and had it not been for some "hand-holding" by Ann Bens, and an obscure reference in another thread, would likely have not figured out why/how I could edit FLV's so easily - on my laptop only. Since I got around to using this plug-in, I have been very impressed and will buy a second copy for the workstation.