Gifs were incorrectly being loaded by a video tag when advanced previews
was set to "Input Only" (the default). The logic for when advanced
previews are used as been clarified.
Resolves#435
Parameters that determine the output quality when advanced previews are
displayed have been moved to only be set when the request if for an
advanced preview. These were ignored when the request was made to the
default /view endpoint, but created undesirable clutter
Austin Mroz
972c87da57