...
For extracting out hidden form fields, I used a simpler regular expression than the one abovein the article: id="__PREVIOUSPAGE"\s*value="(.*?)".
(I'm reluctant to replace it though the one in the main article, unless I know the reason for it). Note the '?' used to specify non-greedy regular-expression matching.
For pages that had 'jammed-in' pipe-delimited data, I use this type of regular expression instead:
|__PREVIOUSPAGE|(.*?)|