that problem lies with the authors of those programs and extensions who do not write with kmeleon support in mind.. they write for ie and firefox and other browsers, then we try to do our best to integrate their stuff with kmeleon.
integrating orbit is fairly easy compared to others, after you download the orbit downloader, install it in its default path:
make sure it installs to this path: c:\program files\orbitdownloader
now download this file: (right-click: save target as)
save this file to your kmeleon macros folder
if you installed kmeleon in its default path, this would be:
after that, restart k-meleon, now when you right click inside a page, you will find a new entry in the context menu called 'orbit monitor', select orbit monitor and grab.exe should open.
now with grab.exe running, you will find a button called action, click on that button and a menu will popup, select preferences from that menu and the preferences dialog will open, click on the monitoring tab at the top and under monitoring, you'll find a custom entry, select it and then click on the 'browser..' button, an open dialog will open, point it to where k-meleon.exe is and select k-meleon.exe, so now it shows the path of k-meleon.exe under custom, click ok to save settings and close preferences.
now when you go to youtube, just right-click and select orbit monitor, grab.exe will open and display the downloadable files on it(or any other site with streaming videos). the actual flv video will not be shown inside grab.exe until you click the 'play' button for that video.. that video should have an flv extension and in youtube; that file will normally be called 'get_video'.flv. select it from the list and click download to pass it on to orbit to begin downloading.