Somebody shared it somewhere most likely. Some share spikes last longer than others depending on where or who shared it. If you get lucky this will be just the start, sometimes a website will post to their site, then an hour or so later post to their Facebook wall and then it REALLY blows up. This one really surprised me back last may, right where you see the blue starting was right after I got a Tweet saying to check their website. The huge spike is when they posted to Facebook... Haven't had one like this since then which makes me sad. In about 2 days you'll be able to click playback locations/embedded views and it will likely have a spike. Here's where you can find what website it was shared on. I have tracked things like this down and found ways to have them share more videos sometimes on my smaller spikes.
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