A quick question regarding the preview video.

I’m about to upload a .zip file and the preview video of my product is 1920x1080px. I saw I have to specify the resolution of my preview video(960x540px or 640x360px).When uploaded, is it automatically compressed to 960x540px/640x360px or do I have to export it with these specific dimensions?
Thank you in advance for the replies.

Word on the atreet is that you can upload 1080p, specify that it is 1080p, and it will be 1080p. Don’t hold me to that though!