It's posible in FMS to record thumbnails of a streaming video in the server side?

Yes.

In a server-side script you have to grant permission to access the directories on the server that hold the streams.

Set Client.videoSampleAccess = "/" to grant access to all of an application's subdirectories.

http://help.adobe.com/en_US/FlashMediaServer/3.5_SS_ASD/WS5b3ccc516d4fbf351e63e3d11a11afc95e-7ec3.html

application.onConnect = function(client){

// grant access to directories that hold streams

     client.videoSampleAccess = "/";

// accept connection

     return true;

}

In your client-side code, call BitmapData.draw():

http://help.adobe.com/en_US/FlashPlatform/beta/reference/actionscript/3/flash/display/BitmapData.html#draw%28%29

You can also access audio data. Set client.audioSampleAccess on the server and call SoundMixer.computeSpectrum() on the client.

The SWF calling the client-side code must run in Flash Player 9.0.115.0 or later.

HTH,

Jody