Use of manual painting in video

[Alan]

Hello all,

Quite new here and still learning SA4 & 5. 

I wish to add manual painting into video as an alpha layer (just the painting or drawing) on top of video footage (so without white or black background) with probably chroma key in the editors. How do I do that and what file format to save it in SA? 

Hereunder an example as a .mov file 

I appreciate your inputs.

Thanks.

Alan :-)

Capture_17.mp4