what version of core-demo do you use? I've just tried one from trunk (http://anonsvn.jboss.org/repos/richfaces/trunk/examples/core-demo/) and it builds and deploys fine. You can also try our testing application Metamer (http://anonsvn.jboss.org/repos/richfaces/modules/tests/metamer/trunk/application/) which contains even more samples.
Hi Palo! Thank you very much for your response.
I've checked MediaOutputBean.java at trunk (http://anonsvn.jboss.org/repos/richfaces/trunk/examples/core-demo/src/main/java/org/richfaces/demo/MediaOutputBean.java) and it has the same "problematic" lines as my local file does:
line import org.richfaces.util.Util; - Eclipse IDE claims that "the import org.richfaces.util.Util cannot be resolved"
line Util.copyStreamContent(stream, os); - "Util cannot be resolved"
Thanks for pointing me the other example.