Dec 7 2015
I support Pginer-WMF's comment above. If a "contact" is needed, File Talk is the best option. Most authors and uploaders are watching them if interested.
Dec 4 2015
See examples like https://commons.wikimedia.org/wiki/File:Libellago_lineata_male-Kadavoor-2015-08-21-001.jpg and https://commons.wikimedia.org/wiki/File:Monkey_Puzzle_Rathinda_amor_by_kadavoor_edit_by_b%C3%B6hringer.jpg. In both cases, the contact should be to me as the uploader can't help much. In the second example the uploader just removed a part of leaf from the photo. In many cases, last uploader do such small edits, like removing chromatic aberration, etc. Some people uploads separately (as in that example); so "first uploader" is not reliable in such cases. For some PD works where author is no more available, uploader may be helpful. But as a generic contact point for all types of works, the file talk page or Commons Help Desk may better (if we really need a contact link).
Dec 1 2015
I fully agree with Pete F here; there is no need to mention first, last or any intermediate uploader in Media Viewer. Earlier some bots mentioned uploader name in source or author field in Commons; now we're removing it. Out priority should be to provide only important (especially copyright-wise) information to the viewer/re-user. That should come from TASL - Title, Author, Source, License; not from any other field. MediaWiki software not supporting a "title" option; so we're using description instead of it. Date also can be mentioned as it helps to know whether copyright is expired. So the current layout is good except the inclusion of "Uploaded by". People may not well differentiate the difference between "Uploaded by" and "Created/Copyright by". So better avoid that unimportant (copyright-wise) field. (Copying from Extension_talk:Media_Viewer/About#Misleading_.27You_need_to_attribute_the_author.27_button_output)