How to setting Opacity of a Video over image in FFMPEG

I have a ffmpeg code which setting Opacity of a Video over image (Instruction in 10.18.1 Examples of FFMPEG Docs):

ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv

I want to setting Opacity of Video Overlay into 0.2 and resize Video Dimension same as Image Dimension.

Need your guys help!