The share failure could be caused by a corrupt frame or clip in the project, or perhaps insufficient disk space on your hard drive to contain the shared out movie. Since it is a large movie, the latter likely is the cause. Check your available drive space and free up sufficient space if necessary, then try sharing again. If still not working, you will need to scroll through the movie looking for black frames, white flashes, artifacts, or other evidence of corruption, and cut those out. You might start at or near the 95% point where the share seems to fail. Work with a duplicate of your project so you retain your original.
Also, try sharing out directly to a USB stick that has sufficient capacity to store the movie. The USB drive should be formatted ExFat or Mac OS Extended (Journaled). Most USB drives are formatted Fat 32, a Windows format, that has a 4GB limitation for any one file. You don't want Fat 32 format. ExFat, on the other hand, is compatible with both Windows PCs and Macs, and smart TVs, and has no file limitation. Mac OS Extended (Journaled) would work fine on a Mac but might not work with Windows computers or TVs. I would recommend the ExFat format. If you need to use the Disk Utility app on your Mac to reformat your USB drive be aware that reformatting erases all data on the drive. So back up all data that you want to keep.
-- Rich