1. Print the time.
print scalar localtime(time) , "\n";

2. Run the program from your Perl script. Get the output of that program into a variable.
my $output = qx(wget http://URL);

3. Munge the data to get what you want.

my ($time, $kb_s) = $output =~ /^(\d+:\d+:\d+)\s+\(([\d.]+)\s+/m;
print "TIME: $time\nKB/S: $kb_s\n\n";
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4. Repeat step 1.

Step 0. RTFM. Thanks for this great link, cacharbe! (I stole it from 138902.)