I understand that you have a 30GB+ video file on your iPhone and you would like to import/transfer it to your Mac. I also understand that you have attempted to upload the video file, from the iPhone, to iCloud in the hopes of having that file on the Mac by syncing it to iCloud.
You have the right concept, however, you also have a huge video file. It will take a long time to upload the file to iCloud and then having it sync/download on your Mac. Do have enough space on iCloud to accomplish this?
There is an easier and a better way to import photos/videos directly to your Mac and without the use of iCloud. It involves the process of connecting your iPhone directly to your Mac with the use of a Cable. Details of this process are listed here 👉 How to transfer photos and videos from your iPhone to your Mac
Axel F.