The other thing to know is that content distribution networks (CDNs) are rather complex nowadays, so it's not merely a question of "my connection to example.com

The other thing to know is that content distribution networks (CDNs) are rather complex nowadays, so it's not merely a question of "my connection to example.com is laggy" but more like "how is data from example.com getting from their servers through caches/load balancers/round-robin/co-locations?" When I took a course five years ago, our instructor said a few words on "Net Neutrality" and he explained that many companies who distribute content, like Netflix, positioned their servers, or at least caches, right where the ISPs are. Now, YouTube might only use Google's data centers for distribution; I don't know. There is also the question of whether Comcast perceives on-demand video as a competition for their own Cable TV services, and whether they're actively throttling video traffic that isn't their own content. Hopefully that would be a well-known fact.