I'm not sure that I understand what you try to do.

If you click a link that isn't handles by a plugin then you get an "Open with" download pop-up dialog.
That dialog doesn't allow to copy the URL to the location bar.

See "File handling in Firefox 3 and SeaMonkey 2"

• http://kb.mozillazine.org/File_types_and_download_actions

The "open with" tells it what to do with the file after it downloads it. I don't want it to download, I want it to stream (which vlc will do if you give it a URL). I want it to run vlc with the command line:

vlc <URL>

Thanks for your help.

If the file is send with a proper MIME type than you should be able to set an automatic action and clicking the link is sufficient to pass the link to the VLC program without seeing a download dialog. That works for me with RealPlayer (ram, rm) files on Linux.

Well I haven't found a way to make it do that yet, that's why I'm here asking. Hopefully somebody knows how to do it.

Everything I can see about applications specifies an action to perform on the file after it is downloaded.

I was hoping that defining a new protocol would work. I went into about:config and set up everything I could find to make vlc:// work as a protocol handler, but it didn't work. Maybe somebody knows how to make that work.

I did figure out how to make Firefox run vlc with the URL, but it was by defining a protocol so I could say "vlc://..." This will indeed run vlc and hand it the protocol, but vlc doesn't know how to handle a URL like "vlc://...".

Another solution I fould was to have my page download a little .XSPF file which had the URL in it. vlc knows how to parse this file and it will play the video.