Do regex on page DOM...
(?<=comment"\ data-author-id=")[\w\W]*?(?={-Variable.commentUser-})|(?<=comment"\ data-tag="top"\ data-author-id=")[\w\W]*?(?={-Variable.commentUser-})
commentUser является наименование, указанное на комментарий. Возьмите первый матч.
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Regex above variable.....
(?<=data-id=").*?(?=")
Все матчи к списку
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Get count of lines in above list. Do a javascript and subtract 1, put to variable and then take line from list matching the variable.
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Then some C# code to click on the resulting Data ID.
https://www.dropbox.com/s/977qrv69y4rbdna/Click Thumbs UP.xmlz