Comment 4 for bug 1499889

Hmm, in fact not only the "--interaction" argument is missing.

This is not a serious patch, but the issue can be worked-around by adding the following lines after line 90 in /usr/lib/python3/dist-packages/sessioninstaller/gstinstaller.py:

parser.add_option("", "--interaction")
parser.add_option("", "--desktop-id")
parser.add_option("", "--startup-notification-id")

After this monkey-patch, Totem shows me the dialog to install missing codecs.