Are there any freeware video decoders for windows media player 10 or above?
Well, windows media player uses the DirectShow backend [which handles all filters/decoders etc.] The problem is, what do you want decoded? What sort of video? There are many many many decoders and encoders - you need to know what you are trying to decode. Try to download G-Spot Codec Appliance and run it on the file to give you an idea of what decoders you will need.
Just a suggestion, commonly people ask for a freeware MPEG4 [H263] type [streams in AVI] decoder - xvid, and ffdshow are freeware video decoders for that specific encoding.