We too have the same problem with the batch download. The JRE does run/prompt to run depending on the browser and the security settings but sometimes what happens is due to the wide range of clients connecting, they might not have permission to run the Java applet or install JRE. Isnt there any way for a non-java enabled browser to batch-download? One thing we noticed was if the user does not run the JRE the browser freezes and only closing it works.
Kindly include support for Resume option and directory download also in the web client in the next release.