Update, April 19 at 15:00 UTC: Several people on Twitter have pointed out that what is seen in this video is most likely not the capsule and deployed arrays, but actually the upper stage of the Falcon 9 rocket and the ejected solar panel covers. That does seem likely to me given the scale of the objects, so I have sent Legault an email asking him about it, and I will update this post again when I know more.
Correction, April 19 at 15:15 UTC: Aha! Yes, I do now think what we are seeing here is the upper stage of the Falcon 9, the Dragon capsule, and the two solar panel covers (used to protect the Dragon's panels during launch, and which are ejected before the panels are deployed). What I somehow missed at the end of the video are the silhouettes of trees in the distance. That gives a sense of scale to the video; the Dragon capsule itself plus the solar panels would be far smaller than seen here. Also, around 30 seconds in you can see the stars of the Big Dipper in the background, showing the field of view of this video is far larger than I had originally supposed.
So to be clear, this is NOT just the capsule and solar panels, it is a larger set of objects that are physically separated in space by quite a bit, making it much easier to photograph them. This is still a cool video, but it isn't the technical achievement I first assumed. I have struck through the original text below and added the correct info.
Thierry Legault is a gifted astrophotographer renowned for his footage of the International Space Station and (once upon a time) the Space Shuttle that he takes through his telescope. His ability to capture these rapidly moving objects is nothing short of spectacular, and I always think there's no way he can top what he's already done.the Dragon for the two or so days it takes for it to catch up to the space station). To give you a sense of scale, the capsule is 7.2 meters (24 feet) long and 3.7 meters (12 feet) wide. The panels are about 16.5 meters (55 feet) across. It was roughly 370 km (230 miles) above the Earth's surface when he shot this.
What you're seeing here is wide-angle footage, showing the upper stage of the Falcon 9, the Dragon capsule, and the ejected solar panel covers moving along together in orbit around the Earth. This was taken a few minutes after the capsule separated from the rocket upper stage, so all the individual things you see here were still near each other in space. Over the next two days the capsule itself will "catch up" the space station and be grappled on Sunday.
So yeah Legault is the best. I've written about his work, many, many times; go read it. Trust me here: You'll be astonished at what people can do when they're at the top of their game.
Congrats to Thierry for this achievement, and to SpaceX for another successful launch!