1) Verizon decided to enter some router configurations that affect the packet forwarding to Netflix (well, most likely FROM netflix, as the internet is not actually symmetrical). What we should see as a result of this is a sudden change in bandwidth.
2) The load on the interfaces in between is changing, either because of more netflix subscribers, more AWS traffic, or more netflix traffic. Since these are things happening slowly over time, you'd see a gradual worsening of traffic conditions.
I think it's pretty fucking likely that what's happening here is 2). Now granted, Verizon could solve this problem by cooperating with Netflix. But for them that's an expense with no upside, so likely they're demanding Netflix make it worth their while to upgrade the interconnects.
This is one of the basic problems with the internet today. It used to be the case that bandwidth between providers was much more plentiful than last-mile bandwidth. So we upgraded last-mile bandwidth. Problem : doing that resulted in an exponential increase in load on the core network and the interconnects between different networks. Needless to say, nobody can keep up with exponentially rising demands (especially without subscriber growth). The basic problem is that a linear increase in bandwidth for the customer results in an exponential increase in costs for the ISP (so -surpise- small ISPs don't feel the effects nearly as badly).
So ISPs are desperate. Their costs are spiralling out of control, with everyone demanding they follow this exponential curve, but of course their customers not willing to pay for it (and all the money in the world would only buy time if thrown at this problem). Demanding the ISPs pay for it is simply not going to work. Right now, yes, they could theoretically pay for it, but that won't last long.
Plus Netflix is being a rather bad netizen themselves. The polite thing to do is to carry the traffic to very close to the user on your own network, and only use other's links, especially transit, as a last resort ("cold-potato" routing, for content providers). Netflix has caches, but no own network.
There's other problems that result from this cost problem. Already transcontinental and other long-haul links are strained to the limit. This has resulted in a massive degradation of non-local internet traffic, and it's getting worse fast.
It is really a very simple problem. You have consumers, and you have producers. And you get more and more of each. To a limited approximation you can assume everyone on the internet is both. To simplify things, let's say everyone uses a tiny amount of everyone else's services. Now given N participants in the network, what is the load on the core network ?
N * (N - 1) =~ N^2 (assuming full duplex links, which would be generally correct for the internet)
So adding more participants in the internet increases resources required to give every existing participant in the network his "old" speed. These need to be paid for. But unless everyone want to start paying an amount for your internet connections that rises with the square of the size of the internet, we're going to see progressively worse and worse throttling. Right now the strategy is fast becoming limiting interconnect capacity to prevent the core network overloading, which would have far worse consequences.
While, yes, historically this has mostly been monopolies cheating the market, that's less and less true. This is going to get worse, fast. And since those resources are obviously not going to be made available, there's only one thing to say :
Get used to it.