Cafedave posts a great link to some Flash MX undocumented features. In particular, undocumented ActionScript such as NetStream which helps further control the use of MICs and CAMERAs in Flash MX content.
http://chattyfig.figleaf.com/flashcoders-wiki/index.php?Undocumented%20Features
Some of the other undocumented ActionScript code features includes:
MMSave
Cookie
Video.prototype.attachVideo
XMLNode
XML.prototype.constructor
ASSetnative
ASSetPropFlags
Netstream
AsBroadcaster
infinity
ASnative
ASconstructor
NetConnection
Object.toLocaleString
Object.isPropertyEnumerable
Object.isPrototypeOf
Object.hasOwnProperty
Object._listeners
System.security.allowDomain
System.ShowSettings
System.Product
System.Capabilities.input
System.Capabilities.serverString
System.Capabilities.isDebugger
System.useCodepage
Accessibility.SendEvent
Stage.broadcastMessage
Key.broadcastMessage
Mouse.broadcastMessage
Selection.broadcastMessage
Sound.prototype.setPosition
Sound.prototype.setDuration
More can be found at the Flash Coders Wiki site
http://chattyfig.figleaf.com/flashcoders-wiki/index.php