The following is a malformed regular expression:

while ($CONTENT =~ <div class=\"usertext-body may-blank-within md-cont
+ainer \"><div class=\"md\">(.+?)<\/div><\/div><\/form><ul class=\"fla
+t-list buttons\"> //gs )
[download]

It is at least missing the s/ start.

Personally, I suggest that you do the content extraction by using HTML::TreeBuilder and XPath or CSS selectors (via HTML::TreeBuilder::XPath and HTML::Selector::CSS).

Also note that Reddit has an API available, so you maybe don't need to scrape at all but can get the comments in a machine readable format directly.

Also note that on CPAN, there are many Reddit modules available, and it seems that Reddit::Client is using the Reddit API.