I am rather late to this party but assuming your records are all seperated by a single blank line and there are no superfluous blank lines then this rather obfu looking one liner will get you there

perl -pe'BEGIN{print"__BEGIN__\n"}s/^\s*$/__BEGIN__\n__END__\n/;END{pr
+int"__END__\n"}' <file>
[download]

Or the mildly shorter but fiercly uglier

perl -pe'$e="__END__\n";BEGIN{$b="__BEGIN__\n";print$b}s/^\s*$/$b$e/;E
+ND{print$e}' <file>
[download]

Cheers,
R.