use strict;
my $str = '00:00:02.736 --> 00:00:06.072 line:79.33% position:10.00% align:start
AND YOUR GRACE?
00:00:06.072 --> 00:00:08.875 line:74.00% position:10.00% align:start
WHAT WILL YOU DO
ABOUT THAT?';
my $regex = qr/(?sm)^(\d{2}:\d{2}:\d{2}\.\d+) +--> +(\d{2}:\d{2}:\d{2}\.\d+)((?:(?!\r?\n\r?\n).)*)/p;
my $subst = '|';
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