download preview has mp4 format and download has mov format

When I download preview for any stock video then it has mp4 format which perfectly blends with my projects and object is keyed out easily from its background. But when I download stock video and add license then it downloads mov format which doesn’t blend well with my projects and i can’t key out the object. It has blackish background and i can’t key out object easily.
How can i download mp4 format?