On the Macintosh, you have to add a wrapper application for the jar-file. Drop the Jar file onto MRJAppBuilder's icon, select the Properties file 'ptproperties' included in the PTVJ package, and set an arbitrary output file name. Then execute MRJAppBuilder. Again, you have to properly set the codebase tag in the separate html file. The 'default.html' file in the archive is ignored by the applet.
Disadvantage is the somewhat larger filesize since more java classes have to be included.
JMF-Media don't work. Some older systems can't read jar-archives at all, eg Netscape 4.03 can read the java classes, but nothing else, not even images. Applications on pre 1.2 systems can't process sound.