0003-mvm-video has an inconsistent width between the resource and the canvas

[digitaldogsbody]

I know this is allowed under the spec (and indeed covered explicitly in 0004-canvas-size) but it seems a little confusing to have that happen in this recipe. I didn't notice it till my recipe implementation checker for iiif-prezi3 flagged that the example script for this recipe was generating non-matching JSON.