Uploading wikia images

Frustration in Excelsis
Notoriously Divine Tagger - Consistently uploads images above and beyond the minimum tag requirements. And/or additionally, bringing over the original description from the source if the image has one. Does NOT apply to the uploader adding several to a dozen tags after originally uploading with minimum to bare tagging.
Artist -
Cool Crow - "Caw!" An awesome tagger
Magnificent Metadata Maniac -

Worldbuilding Addict
I prefer to upload screencaps from the mlp wikia when I can, because they’re usually of better quality and resolution than the ones I take myself, and I’m running into a bit of a conundrum.
 
If I try to upload using the url of the full-screen image you get when you go on the image’s wiki page and click on the image itself again (as in this one, using a screenshot from “Rock Solid Friendship” as an example), I get an error message saying that the site was “Unable to find a valid image at the URL you have provided.”
 
If I try to upload using the url of the image’s “regular” page (like this), it loads more or less fine, but the image preview that appears over the url box is invariably blank with the white-question-mark-in-a-blue-box icon that signifies that a picture didn’t load or couldn’t be retrieved. This happens with every image I’ve tried, and while the uploading process maybe could still work, I’m hesitant to try in case something does go wrong and a botched image is uploaded.
 
If I save the image on my computer and upload it that way, as I usually do, everything works but the resulting picture is always quite a bit smaller than it is when it’s on the wikia – as an example, compare the sizes here, on Derpi, and here, from the wikia.
 
So, my question: is the anything that can be done about this? Can I go ahead and upload directly from the wiki? Would that even do anything? Or am I just better off sticking with what I’m doing so far?
Background Pony #FAC4
@Frustration in Excelsis  
Try removing /revision/* from the direct url so it ends with the file’s extension (e.g.). It should be fetched correctly this way.
 
If I save the image on my computer and upload it that way, as I usually do, everything works but the resulting picture is always quite a bit smaller than it is when it’s on the wikia – as an example, compare the sizes here, on Derpi, and here, from the wikia.
 
You mean, the file size? Derpibooru optimizes uploaded images so of course it’s smaller, this is nothing abnormal.
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