This is something that I've been experiencing for a while now:
Yep, I can't control a mouse well enough to use YouTube.
Admittedly, this particular instance of me using the site's volume control is contrived and exaggerated, I have been experiencing off and on problems adjusting the volume on YouTube videos for a while. While this might be a classic example of Fitts's law, it is certainly related, and, not only do we have a small mouse target for the volume control, but it also changes size on us.
Given that the videos hosted on Youtube can vary quite a bit in volume and/or sound annoyance, I'd suspect that the volume control is used quite often. It would make sense to have it work well.