I am new to Blender(2.9) ,I followed several Camera Tracking tutorials. But when I render my final image, it only renders the 3D objects and the video image doesn't get rendered.If I change the "Fac" value of the "Alpha Over" node, it blends the images but does not give the result I want . (all the tutorials keep this "Fac" value to 1.000)
Following shows my View Layers,Collections (I deleted the 'BackGround' layer generated by the Camera Tracker)
This shows the Compositor settings:
Any tips on how to fix this ?