for windows/
it is not the right question :
you want to read a movie "divx, xvid, etc..."but you cannot , why ?
to read (audio or video) you need only be able to, from owners of the films or the sings...
this commercial question is resolved : divx 7 (free)
: wmp 11 (free) + codecs (look for to add it)
: mp (classic or homecinema) (free)
works on whith ffdsshow
but take care, linux have another solutions (free) and another players...add codec you need from your package..