It would have been better to actually show sanding and polishing the parts, as to direction of sanding as well as polishing. Then you would have been instructing not just showing results.
The direction is not critical as long as the sanding is thorough. Sand lengthwise, around and even diagonally as required to get to every inch of the surface. Do the same thing with the polishing.
I did another video that involved polishing and painting and decided to take your advice about showing more of the work. ruclips.net/video/sAYpptKqB0I/видео.html
It would have been better to actually show sanding and polishing the parts, as to direction of sanding as well as polishing. Then you would have been instructing not just showing results.
The direction is not critical as long as the sanding is thorough. Sand lengthwise, around and even diagonally as required to get to every inch of the surface. Do the same thing with the polishing.
I did another video that involved polishing and painting and decided to take your advice about showing more of the work. ruclips.net/video/sAYpptKqB0I/видео.html