Comment 1 for bug 751101

There's actually multiple bugs here.

The only Firefox bug is that you even get offered to open mms links in totem at all, because totem doesn't have x-scheme-handler/mms defined in its desktop file. Once bug 727372 is fixed, Firefox will (correctly) display an error message saying "Firefox doesn't know how to open this address, because the protocol (mms) isn't associated with any program."

If totem can handle mms links, it needs to declare this in its desktop file (which is a totem bug).

Thunderbird only works because it is still using gnomevfs, which is deprecated anyway and will stop working in the future too (but we will have proper gio support then).