Even some network media players support FLV format, so it is not that bad.

Also note that DVDs don't have to be with AVIs.... Many portable players support .MP4, .MKV video files.

And what do you mean by editing? Just splitting or removing some parts?

If your FLV files use h.264 video codec, I recommend to try

1. to remux them into .MP4, .MKV or .AVI first,
2. to remove parts of your video with AviDemux

Both can be done with AviDemux.

As for Xvid and other codecs, if you change settings (like bitrate), you should be able to get a comparable size. Although sometimes your files will become bigger.