Fixes a segfault when there is a typo in the <encoder /> setting.

It's no longer relevant.

This reverts commit b0ef65fc.
It's been nicer to read before, and static analysis can ignore this one.

... but keep it in cmdline.c (for now) to "follow the pattern".

Adds support for WebM/Matroska
Replaces Vorbis and Theora with Ogg

It's causing too much trouble in testing.