I've noticed that some of the videos have an advertisement that pop out to the side where the lyrics section usually is. Normally I can just click the 'X' button in the corner and it will go away. However, other videos contain ads that will not vanish when you click the 'X' button. There is nothing to click on it to make it go away and if I scroll up and down, it will follow the motions (going up and down too). It's been driving me insane! I'm not sure if anyone else is having this issue, but if so we would love it if someone who works for the site could fix this.
P.S: Two of the videos having this problem are Marina Inoue's "Houseki" and Ayumi Hamasaki's "Progress".