Comment 10 for bug 38584

I'm sorry if I gave the wrong impression with my previous comment - it was just a set of comments on my findings so far.

To answer your questions as best I can:
if you open a URL in the address bar with mms:, then a helper application will be called. That can show the URL in another window. However, that isn't much use when trying to use a plugin.

The debug messages you see are just debug messages, and don't help with this problem. The nsPluginInstance comment is a reference to the way Netscape/Mozilla/Firefox communicates with plugins, though it's difficult to get good documentation on this :-)

The model used by totem is that firefox downloads the content, and passes it to the totem backend. I don't know why the URL is passed to totem, and the argument doesn't look like it was used. This model makes sense for http: and ftp: URLs, but NOT for mms: URLs, as firefox cannot handle them itself (I think).

My proposed way of handling this would be to check if the URL passed to the plugin starts with mms: - if it does, then pass the URL to totem instead of fd://0.

I will be attaching a possible fix in a minute, though it does need a bit more testing than I have given it so far.