Well, that's confusing. It looks like the error is on VideoServlet.java. VideoData.java has already been compiled, but somehow has the wrong version in it. Have you tried "ant clean"? It's just possible that you have an old class file hanging out there somehow. Also, I believe the JDK version used by ant is going to be what is specified in the JAVA_HOME environment variable.
You should make sure that matches up with the version that you'd get from running from a command, that is, the one you get from your path.