Você pode tentar o Moyea FLV Editor Lite .
Moyea FLV Editor Lite is a free FLV editor especially designed for FLV files. With this editor, you can edit YouTube, MySpace, blogTV, etc. The editor does not recode the FLV files, so it perfectly keeps the original quality. The notable thing is it enables you to edit FLV with timeline to trim FLV video length, split FLV duration, rip FLV audio and video, replace the FLV audio, add cue point and metadata, etc.