Hi there ZechariahGithinji,
It looks like you are getting this error after following the steps outlined here: If Cinematic mode videos from your iPhone don’t appear when importing to your Mac or Windows computer
If so, how long into the processing progress does this error appear? Are you staying in the Photos app during the entire process or are you exiting out or letting the device go to sleep? We ask as this can affect the processing of the videos.
Also, ensure your iPhone is fully updated since this installs feature improvements and bug fixes that can resolve unexpected behavior like this. These steps from Update your iPhone or iPad show how to back up and update:
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see more than one software update option available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
Take care!