When debugging regular expressions (and the text they should match against), I find a good technique to chop off elements from the regex until it matches:

my $line = 'amss\products\76xx\wconnect\bthost\brew\statext\src\aeebte
+xtag.c-36572;FILE.flf;//source/wconnect/bthost/brew/statext/rel/00.00
+.26/src/AEEBTExtAG.c - LABEL : 1';

print "Has ;/"
    if ($line =~ /;\//);
print "Has ;\/[^\/]"
    if ($line =~ /;\/[^\/]/);
print "Has ;\/[^\/](.*)\s-\s"
    if ($line =~ /;\/[^\/](.*)\s-\s/);

(my $file_name) = $line =~ /;\/[^\/](.*)\s-\s/; 
print $file_name;
[download]

That way you can easily see in your program where the matching stops. You could also use re 'debug', or output messages when the regular expression engine backtracks, but I found it always easier to manually create the relevant steps to output where my match progresses.