It was a little game to adjust the telemetry to the converted video. But at the end it is done. I tried to switch to FCC but I couldnt, so it was in normal CE mode.
Make sure you're loading the correct Flightplan, otherwise the drone might just go somewhere else.
You will probably be better flying more than 3 metres above the water so any birds which are startled have space to fly into without crashing into the drone. A duck or goose colliding with the drone will result in a crash. When they have got to over 3 metres above the water they should have the skills to avoid hitting your drone.
I have done a flight plan over a lake which was at 12 metres, this was enough to go over the top of any yachts.
The controller will tell you that if the signal is lost the drone will return home. This is NOT TRUE in Flight Plan mode. The drone will continue with the flight plan providing it has enough battery to continue. If the drone decides that it cannot complete the flight plan without running out of battery power it will return to home directly. There is a possibility that it can use too much power on one leg and then not have enough power to complete the return to home. If that is the case all you can do is hope you are still in contact and can direct it to a safe place to land.
Always have the final point on your flight plan close to where you will be stood. You can start and finish a flight plan on the ground if you want to, I prefer to have the start and finish position about 20 metres away from where I intend to stand, up in the air, away from any trees or other obstacles. I once made the mistake of planning a giant long-range flight plan which would inevitably result in losing the signal but the final point on the flight plan was 1km away from where I was stood. I got away with it but it was a very stupid thing to do. The other reason to have the flight plan finish back where you are is that you can see how long it is likely to be in the air. If the plan says it will take 18 minutes don't do it! That will give you no margin for error. I try to keep all my flight plans down to 12 minutes or less.
When you start a flight plan it defaults to flying the legs between waypoints at 5 metres per second. I expect with a big lake to fly across you will want to select a higher speed. While the Anafi can reach 15 or even 18 metres per second the highest speed you can plan to fly is 11 metres per second. The normal RTH speed is about 10 metres per second.