If you watch the slow-motion carefully, you can see that the rear tire maintains traction while the front of the bike slips out. In other words, he crashed because he lost grip on his front tire. I don’t see the brake lights going on, so I don’t think he braked. Similarly, though you can’t really tell from that angle, his body position didn’t seem horrible (not leaning much more than he needed to), I don’t really think he was leaning that hard.
Not too confident, but my vote’s on slick road surface (sand, oil, etc.) or bad tires. He went down REALLY fast without leaning much. If his tires were too new, too worn, or too cold, his lean angle might have been too great. All the same, it really looks to me like somebody hitting an oil slick or sand patch.
One thing you’ll notice is that he crashed on corner exit. Leading up to the crash, his engine was spinning down (listen to the engine sound), despite the fact that he was coming onto the straight. For whatever reason, this is wrong on his part. For one, by the time you hit corner apex (at the LATEST), you should be back on the gas. If you’re a conservative street rider (which I’d hope for), you’d be on the throttle again (slightly) immediately after turn-in. Getting on the gas helps stabilize the bike and move some weight back to the rear tire. In combination with standing the bike up more as he came onto the straight, this may have taken enough weight off the front tire and reduced lean angle enough that, even with a poor road surface, he may have kept the bike up.