Fix issues pointed out by aarcos

See https://gerrit.wikimedia.org/r/#/c/95282/10/resources/ext.multimediaViewer/ext.multimediaViewer.js

A few issues with code being in two places; should probably refactor but
would prefer to get out a fix and refactor a little later.

Change-Id: Id74a01e177aeb09fe34416e7fd14759df58fda32
Merge "Fix issues pointed out by aarcos"