Checking that seconds box is only to filter the seeds generated for an specific second. You can check it if you want, or not, it won't change anything whatsoever. The +/- is to represent a range of seeds found around the seed you're trying to hit. If you miss your seed and try to look for the seed you actually hit the reporter will only look into this range. You might think this is a great idea, however, because the same sequence of calls / flips can happen at various times, you might end up with a false positive.