Basically this feature is an auto-organizer built into LimeWire.

What that means is, is when you download say an AVI it will...
1. Save the file in your primary download folder.
2. Wait till the transfer completes.
3. Auto moves the file to a specified AVI file-class folder (eg. Movies, Videos etc.

So basically the Save to directory needs to read something like this.

1. Primary Download Directory - Where to save temporary files until completed. (Will create an additional folder called 'Incomplete' in this folder.)

2. Video Directory - Where to save AVI, MPEG, OGG etc

3. Audio Directory - MP3, MIDI, WAV, etc

4. Data Directory - EXE, ZIP, ACE, RAR, etc

5. eBook Directory - TXT, PDF, RTF, DOC, etc

6. Misc Directory - Just a folder for anything that does not fit the four above