Your code gives me an error because

print (split)[1];
[download]

doesn't mean what you think it is. The compiler doesn't know whether you mean:

( print(split) )[1];
print( (split)[1] );
[download]

It's kinda like the expression: print (5 + 3) * 4 prints 8, and has a return value of 4 because it's parsed as: ( print(5 + 3) ) * 4. But in your case, since a list slice needs parentheses around the entire list your code causes a compile error (there are not parentheses around print(split)).

You can disambiguate those parentheses with a unary plus, to tell the compiler that the parentheses aren't used for a function call, they just are used as a grouping in the first argument (and the function call is without parentheses).

print +(split)[1];
[download]

Or you could just explicitly parenthesize two levels as above.

Update: not relevant to your specific question, but to your code in general -- you can just replace what you have with:

perl -lnae 'print $F[1]' somefile
[download]

-a does auto split into @F, -n does auto while(<>){..}, and -l does auto newline on print statements. See perlrun for details.