Recently, some have reported having difficulty with sending video files recorded on iPhones to Google Drive. The way to do it is to pull it into drive instead of pushing it out to drive.
- On your iPhone or iPad, open the Google Drive app.
- Tap Add .
- Tap Upload.
- Find and tap the files you want to upload. To upload photos or videos, tap the photos and videos you want and tap Upload.
This seems to work without any problems at all.