Actually I think he does a decent job trying to explain, how Sagan bridged the gap. It's the footage, that comes short. And I think he's right, when he mentions, that Sagan tucks right before the second right hand turn and opens full gas. This also shows the world class rider Sagan is, since no one else could follow him. He is truly a top puncheur.
And true that the germans missed their chance. But Degenkolb actually made the first group, but had a puncture, which is not shown in the footage. And Greipel was the one in no mans land between 1st and 2nd group, but just couldn't close the gap. If Greipel was in better form, more like Sagan form, then he would have been able to close easily. Besides that, if Greipels team had been in place, they would have been right in front of him and could have closed the gap for him. The way I see it, it was Greipels team who failed in helping him to make it to the first group.
But as mentioned by others, the belgians and britons played that crosswind situation beautifully, and most other riders were just caught snoozing.