Suggestion List:
1. Options->Settings:
1.1. Additional file extension for uncompleted download: Default file extension;
1.2. Comment: Option to disable 'Comment' (which can be useless to some (most?) users;
2. View->List of downloads:
2.1. 'Original Web Address' (web address that was given to Free Download Manager to download from (for example, 'www.example.com/'));
2.2. 'Actual Web Address' (web address that is actually is/was being downloaded from (for example, 'mirror1.example.com/'));
3. Downloads->All downloads:
In addition to 'Video' and 'Other':
3.1. 'Music' to 'Audio';
3.2. 'Software' to 'Program'/'Programs';
3.3. 'Archive'/'Archives' (for archives like '.zip', '.rar', '.7z', etc;
3.4. 'Image'/'Images' (for images like '.bmp', '.gif', '.png', etc;
3.5. 'Library'/'Libraries' (for libraries like '.dll', '.lib', etc;
Off the top of head