I'm not trying to be a pain because I'm seriously interested in the results of this test, but the reason it's better to name it a random name and not "clipA" and "clipB" is because they don't always show up in the right order and people vote for the wrong one. Notice that clip B is the first one.
Also, it's better to not explain what the differences are. Show 2 clips and give no information. Let people decide on their own what sounds better without being given preconceived notions.