>Does YT have a quantifiable monopoly it abuses in an economic sense?

I really don't see how YouTube could be seen as anything but anticompetitive in many of its practices. Primarily, the fact that they have used and continue to use revenue driven by search from Google to maintain the tremendous infrastructure necessary to run YouTube. This means that anyone who wishes to compete with YouTube needs to be able to find investors (or pay themselves, but the number of people or organizations that could do that can be counted on one hand) willing to foot the bill to build billion-dollar infrastructure and then expect to run it at a profound loss, burning hundreds of millions of dollars a year for potentially a decade or more. Google is probably making some money on YouTube now, but they ran it at a mountainous loss for years and years for no reason other than suppressing the possibility of competition being developed. There also other smaller things, like the US government deciding to host all of their video content on YouTube without even considering following the legally-required bidding process - because there was no realistic competitor. That's pretty telling.