Interesting perspective. It's really simple if you think about it. The booster just follows a parabolic path. So you have the landing ship facing the launch site just far enough downrange that the booster practically can't miss.
So much to see here.
1) Launch
2) Notice the contrails are wiggly at lower altitudes as they are affected by winds.
3) As the rocket rises, air pressure decreases, and you can see how the rocket's bloom expands.
4) Surprisingly I don't definitively see separation. The booster shuts off, separates, then 2nd stage engines start up. But I don't really see a gap like that. It looks continuous.
5) The ship is something like 3-400 miles down range and separation happens at around 13 miles in altitude. All rough numbers just to prove to myself it happens at a very low angle.
6) I think separation happens somewhere around the clouds.
7) After the 2nd stage clears the frame I think you see the booster. At first, it's just reflecting sunlight.
8) Here's where it confuses me. We see the booster briefly fire the engines for the entry burn. However, it looks like the booster is still gaining altitude. That entry burn shouldn't happen until the booster is on its way back down.
What you think?
Here are some flight profiles for reference.
List of visual launch and landing profiles for each SpaceX mission for easy reference (starting with the Nusantara Satu mission). – SpaceX
www.elonx.net
And just for fun here's a Falcon Heavy profile with two boosters doing an RTLS and one landing on a barge.
spaceflight101.com