To do that, the regexp should be

if ($text =~ /^Total Datafile Size MB\s*\n(.*)^-{22}\s*\n(\d+\.\d+)/s)
[download]

The second number will now be in $2.

While you're at it, you should also change the .* in the first paren with something like \d+\.\d+.

I realize both work right now, but if you get some funny stuff in your file, the stricter version will make sure you don't pick up a non-number.