Having problems with using www and videos

I am using the WWW class to load my movies as I need to load upto 16 movies.
I find that I get WWW: out of memory on some movies. I can not find any reference on why I get this also I get "Unable to determine the audio type from the URL (file:///H|/Trixer/trixterunity/Movies/TV/TV3.ogv) . Please specify the type.
UnityEngine.WWW:get_audioClip()
c__Iterator6:MoveNext() (at Assets/Scripts/HUD/PlayVideo.cs:247)
". I have encoded all the movies using ffmpeg2theora. Can any one show any light on this.

Ta
Mike

OK I have now fixed the Audio Problem

But no luck with WWW: out of memory it seams that when I start the 4th movie I get out of memory Please help if you can.

Mike