This might be it. In the example you can see it's not particularly related to the waypoint angle, as it came to a momentary stop at the left waypoint (4:30). The much sharper angles at the next two may have actually been smoother as they were using progressive course.
It's a little hard for me to see where your mission starts and ends. However, there are some small stops in the flight where the speed is almost 0 m/s. You're right in this should not be so.
I can also see in my log there is a stop of close to 0 m/s every time there is a waypoint. If I fly at 10 m/s on the mission, the speed of most waypoints is 5 m/s according to my log. I just did see that on my video, as I normally fly high and video landscapes.
The fact we must have complained to the Parrot about that! The Flight Planner has to be a much better since we've paid a lot of money to get it.
I have FreeFlight Pro for my Disco, but have not played with the FlightPlan department yet. However, I'm sure my Disco does not come close to 0 m/s when it rounds a waypoint.