The conversion settings that you try to use (AVI Same Quality) don't seem to work here. This is probably because FLV files from cam4 use Nelly Moser audio codec (8000 Hz, mono).

I've tried to recompress audio audio and leave video



but I got weird sounds only.


Then I changed AVI to MP4



and got a playable file.


I still suggest you to try to open FLV files with VirtualDub using the method mentioned above or AviSynth.

Alternatively you can convert FLV video and then edit it, but you will lose quality then.