[Plugin: NextGEN Gallery] redirect images to external offload service

I have high traffic blog and i’m starting to use external offload service for static files to preserve hosting bandwidth limit.

My actual images path for gallery is standard: https://mysite.com/wp-content/gallery/imagename.jpg

I need to change path whit this subdomain: https://static.mysite.com/gallery/imagename.jpg

How can i get it?