if you want something in the video a trail is probs the right thing to use…
Theres a guide here - its very easy all you have to do is add the trail object and also add 2 attachments to represent the width of the trail. You’ll probs want to place 3 or 4 trails on each of the windmillblades and give them different lengths and transparencies…
However this only works if your windmill blades are made from parts…
If they arent you might want to try an animated texture but that is a bit more complex
you can get any texture and just publish it to roblox and then copy asset id. There is a properties section where you can change the time and scale i believe.