Codice per mettere un video nn funzionante

[Mega69]

Come mai quando inserisco questo codice per visualizzare un video, con Mozilla non funziona...

<embed src="video.avi" autoplay="true" />

...e se invece inserisco questo funziona?

<object id="MediaPlayer1" width="480" height="360"  classid="CLSID:22D6F312-B0F6-11D0-94AB-0080C74C7E95" codebase="http://activex.microsoft.com/activex/controls/mplayer/en/nsmp2inf.cab#Version=6,4,5,715" type="application/x-oleobject" standby="Caricamento...">
  <param name="AutoStart" value="true">
  <param name="FileName" value="video.avi">
  <param name="ShowControls" value="true">
  <param name="ShowStatusBar" value="false">
  <param name="loop" value="false"> 
  <embed  type="application/x-mplayer2" pluginspage="http://www.microsoft.com/Windows/MediaPlayer/" src="video.avi" name="" width="480" height="360" autostart="0" showcontrols="1" showstatusbar="0" showdisplay="0"></embed>
</object>

[Mega69]

niente?