Greetings Naet2000,
We understand that your videos are not being imported as expected in Photos, on your iPhone. We suggest that you complete the following steps:
"You can import photos and videos directly to the Photos app from a digital camera, an SD memory card, or another iPhone, iPad, or iPod touch that has a camera. Use the Lightning to USB Camera Adapter or the Lightning to SD Card Camera Reader (both sold separately).
- Insert the camera adapter or card reader into the Lightning connector on iPhone.
- Do one of the following:
- Connect a camera: Use the USB cable that came with the camera to connect the camera to the camera adapter. Turn on the camera, then make sure it’s in transfer mode. For more information, see the documentation that came with the camera.
- Insert an SD memory card into the card reader: Don’t force the card into the slot on the reader; it fits only one way.
- Connect an iPhone, iPad, or iPod touch: Use the USB cable that came with the device to connect it to the camera adapter. Turn on and unlock the device.
3. Open Photos on your iPhone, then tap Import.
4. Select the photos and videos you want to import, then select your import destination.
- Import all items: Tap Import All.
- Import just some items: Tap the items you want to import (a checkmark appears for each), tap Import, then tap Import Selected.
5. After the photos and videos have been imported, keep or delete them on the camera, card, iPhone, iPad, or iPod touch.
6. Disconnect the camera adapter or card reader."
More details here: Import photos and videos on iPhone
If you continue to experience the same behavior, follow this link to connect with Apple directly: Get Support
Best wishes.