I'm no flat earth idiot but I can understand why they find such footage unconvincing. Find some gopro videos of tennis players, take a few stills from their videos and try tracing the tennis court lines with a line tool in an image editor. Straight lines on tennis courts turn into curved lines in gopro footage.

If you're not going to take the time to learn and understand the physics of lenses while attempting to use images from those lenses as proof of a controversial claim, then buckle up buttercup, as the condescending criticism is going to be fierce. Sheer mockery and laughter will be well deserved.