That I know, no way to directly upload from dji Mavic Pro share to YouTube. Which seams rediculess. Assume sites you can down load to pay a fee to be on dji Mavic Pro app.
I download from Mavic to my videos then upload to YouTube or use iMove editor to upload.
the "best" is to save cache video and then share it.. or alternatively is use dji editor(which works always with the cached video) then when you end the project it'll be saved into your internal storage.. then you upload it