Rounded video

Hi everyone, i staring now on motion 5 and ii'm trying tod o a intro for my videos on yt, but i'm trying to put a video inside a bicycle wheel, but i don't know how put the video rounded, can anyone help me?

With the video layer above the bicycle wheel layer:

1. Right-click the video layer, from the pop-up menu select Add Image Mask.
2. Hit "C" to select the Circle drawing tool. Hold the Shift key while drawing a circle roughly the size you need.
3. F4 to the Shape Inspector, turn off outline, make it black.
4. Shift-S for the normal Arrow tool, select the Image Mask layer, then drag the Circle layer into the Mask Source well in the Image Mask's Inspector pane.
4. - Select the Circle Layer, adjust the corners and sides so that it fits inside the bicycle tire.

Thank you BenB.