If your on windows, you could use VMPlayer to create a VirtualLinux PC within windows... Performance seems OK on mine... (I use fedora11)... Once setup I have it now on a dedicated laptop that I just SSH and X11 from...
To view online movies in X, you will probably need the GSTREAMER libraries, "Ugly, Bad and good". I had to add the "Levina" repository (google it) to YUM to get them,
but other linny's might be different... "rpm -ivh http://rpm.livna.org/livna-release.rpm" adds it easily...
Once this was done it was just
"yum install gstreamer-plugins gstreamer-plugins-good gstreamer-plugins-bad"
Once you got the libraries, VLC, Real and other players should be ok for MPeg and Divx movies.
NEAl