use strict;
my $str = '0:04:10.700,0:04:11.360
but
0:04:11.360,0:04:15.680
but it was plenty big you know the silo itself would have easily been
0:04:16.180,0:04:18.420
as wide as this room is
0:04:18.420,0:04:23.200
and perhaps larger and many, many, story\'s tall, you know because it was nested underground';
my $regex = qr/\n*\d+:\d+:\d+\.\d+,\d+:\d+:\d+\.\d+\n(.*)/p;
my $subst = '$1 ';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html