great topic for a video and really useful but please take better videos.
Check the background for light/dark elements (eg bike-stand feet) which obscure your subject edges.
Use a mid-tone even background, like a cardboard bike box to aid auto exposure.
Put more light onto black-pained metal. Make it diffuse, eg North window or reflected from a white surface.
Check your focus.
Don't move the camera so much. Use a tripod or other stand. With free hands you can use a pointer.