IIS and FLV and MIME

In order for IIS to support .flv in a particular website, you'll need to add an entry to MIME Types.

Right click Website, Properties > HTTP Headers > MIME Types

Extension: .flv
MIME Type: video/x-flv

Joining MP3s

Here's a command to join MP3s in a directory into one big MP3.

copy /b *.mp3 c:\new.mp3