I stated to adjust as necessary, because if it's a short file (say 4 lines, which is still a flood risk in itself)..

4 lines listed real fast is no biggy.. If the IRC allows, say, 20 lines before flooding, then a small file is nothing, and 100 is ok. 1000 is still too fast and can cause flooding if it lasts for too long... etc..

Being one paranoid of flooding...
Code:
on *:TEXT:!favorits:#:if (!$hget(faves,$+($cid,#))) { play $chan favorits.txt 1000 | hadd $+(-mu,$calc(30 + $lines(favorits.txt))) faves $+($cid,#) $ticks } }

That *should* prevent someone from activating it from the time it starts to 30 seconds after it stops (if you set it for 1 line per second)