Once again, I'm going to offer you some constructive criticism that you can feel free to ignore.

Think back over all the viral videos you've ever seen- how many of them relied almost entirely on text to make their point (i.e., a picture or two, maybe music, but mostly text flashing on the screen)? I can't remember any, but either way, look at 99% of the most popular videos and pay attention to what they have in common: they all show you something, instead of telling you.

Just using this current video as an example- on the surface, your goal is obviously to communicate that the EPA (et al) said over and over again that the air was safe, but they were wrong, and now people are dying. You direct people to http://historycommons.org to learn more, which is the right thing to do, but you're not really adding much value over what people can find there.

Why not show an actual timeline? Nothing fancy- just a line with labels for each year. Then, after each event is displayed, you add a marking of some sort to the timeline. You wouldn't need to label those markings, because all of the events are so similar. In the end, the viewer would be able to see, in one glance, exactly how many markings are on that timeline & how far apart they are. That image will stick in people's minds.

Then, for the payoff, "1,000s are sick and dying", why not flash a few pictures of suffering first responders up there, in addition to the text? You could even add it as the final dot on the timeline before showing the pictures. Again, the images are what will stick in people's minds. Don't tell them if you can show them (or in a situation like this, do both).

Just my $.02. Oh, and the only reason I'm even sharing this with you is because I've seen you make comments along the lines of, "there's no reason why this video shouldn't go viral".