Last time I ran this at scale was a couple of months ago, so my information is no doubt out of date, but in my experience, YouTube seems less concerned about this than they are when you're grabbing lots of videos.
But that was a few months ago, so for all I know they've tightened down more hatches since then.
But that was a few months ago, so for all I know they've tightened down more hatches since then.