Audio Systems: Blu ray player, thought c, blu ray player

Question
Hello Cleggsan, i have a concern. Certain regular dvds (not blu ray discs) make my blu ray player vibrate and make a weir noise sometimes only on certain scenes of the disc though. The vibration is not severe but enough to feel it and hear it. I check the disc to make sure it's not damaged or warped but the disc looks neat. Is that normal? Would my player be harmed by that? The make and model is Sony BDP-S350 if that helps you. Thanks in advance.

Answer
Probably the disc spinning at a high rate while the servo is looking for tracks on the disc.  The vibration is due to a very slight imbalance of the weight as it rotates.  You can prove this by noticing a difference from disc to disc and it usually a function of the center hole being ever so slightly off center when it was punched at the pressing plant.  

Are you not getting a similar high spin rate with BR discs as well?

I don;t believe it is doing any harm to the player or the discs.

QUESTION: Does it do the same thing when playing a vibrating disc in a conventional DVD player?  That would be interesting to notice.  The searching and tracking mechanism is quite different in a HD or BR player but not all that different.....  just a thought.

C