It was just pointed out to me by Jim Underwood that I left a handler out of this when I originally posted it.
I see I also failed to say the Satimage.osax was required.
Appended is a working script.
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# Auth: Christopher Stone
# dCre: 2016/06/09 03:48
# dMod: 2017/05/01 22:15
# Appl: Miscellaneous
# Task: Get kMDItemWhereFroms metadata from the selected file in the Finder.
# Libs: None
# Osax: Satimage.osax
# Tags: @Applescript, @Script, @Satimage.osax, @Finder, @Shell, @Metadata, @WhereFroms
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tell application "Finder" to set finderSelectionList to selection as alias list
if length of finderSelectionList = 0 then error "No files were selected in the Finder!"
set posixPath to POSIX path of (item 1 of finderSelectionList)
set whereFromsList to getFileWhereFromsUrlList(posixPath)
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--» HANDLERS
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on fndUsing(_find, _capture, _data, _all, strRslt)
try
set findResult to find text _find in _data using _capture all occurrences _all ¬
string result strRslt with regexp without case sensitive
on error
false
end try
end fndUsing
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on getFileWhereFromsUrlList(posixPath)
set whereFromsInfo to do shell script "mdls -name kMDItemWhereFroms " & quoted form of posixPath
set whereFromsURLs to fndUsing("\"(.+)\"", "\\1", whereFromsInfo, true, true) of me
end getFileWhereFromsUrlList
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