I would like to know what is the cause of that even with a video please?

I believe you mean an EAC fail or Electronic Accelerator Control failure. It is basically saying that the engines computer cannot control the electronic throttle. It can be caused by the ECU itself having an internal failure, the throttle body, the wiring or the throttle pedal having a failed sensor. The only way to know for sure is to use a scan tool and see what codes are stored about it and then look at the live data for the parts of the system to determine where the failure is. Repairs then address that particular part. There is no real video on it as the cause is different most of the time. The first step is to scan it with a higher level scan tool that can see all the modules involved.
https://www.2carpros.com/articles/can-scan-controller-area-network-easy
From there you can develop a plan of what to test and how.

Can you please recommend a app that I can used to order my Ford Fusion parts from here in Africa

I'm used to using places that also have a real store simply because there seem to be fewer problems with fake or counterfeit parts. However I'm not sure if any of them ship to Africa. I believe you have to have the parts sent through an international freight service like FedEx or one of the other shippers. I think the common method is to have someone in another country that has the parts available, order the parts and then put them together into a single shipment. Not something I deal with. However you might see if the local dealership has a parts importing system.