Dreamweaver localization problem
Problem with non-english Extension Manager and localization folders

If you use non-english Extension Manager an extension can be installed in wrong localization. In this case the extension won't appear in the Dreamweaver menu "Insert -> Media -> ...". Follow these steps to fix the problem:

1. You need to make hidden files visible
Windows 7 - How to see hidden files
Mac OS - How to see hidden files

2. Find where the extensions are installed
....\Configuration\Objects\FLV_player.htm or ....\Configuration\Objects\fwsgallery.htm

English configuration folder

Windows 7/Vista: C:\Users\<username>\AppData\Roaming\Adobe\Dreamweaver CS5\en_US\Configuration
Windows XP: C:\Documents and Settings\<username>\Application_Data\Adobe\Dreamweaver CS5\en_US\Configuration
Mac OS X: Macintosh HD:Users:<username>:Library:Application Support:Adobe:Dreamweaver CS5:en_US:Configuration

German (German is just example) configuration folder

Windows 7/Vista: C:\Users\<username>\AppData\Roaming\Adobe\Dreamweaver CS5\de_DE\Configuration
Windows XP: C:\Documents and Settings\<username>\Application_Data\Adobe\Dreamweaver CS5\de_DE\Configuration
Mac OS X: Macintosh HD:Users:<username>:Library:Application Support:Adobe:Dreamweaver CS5:de_DE:Configuration

Possibly the extensions installed in the en_US configuration folder, you need to copy the configuration folder to your localization.
Or maybe the extensions are in your non-english configuration folder, you need to copy the config folder to the en_US folder.

3. Copy the configuration folder and restart Dreamweaver.