hidden - missing video

Hi agnieszkaAgga.

It sounds like either you are not using iCloud Photos or perhaps you do not have enough space in iCloud for such a large video file. When you say you can't see the video when connected to your PC, are you using iTunes to try to sync?

Sync photos in iTunes on PC with devices - Apple Support

If you can't import photos from your iPhone, iPad, or iPod touch to your computer - Apple Support

Another option would be to use the Share option in the Photos app on the iPhone to send the video to the Files app and save it to iCloud Drive (again, that will be dependent on the amount of iCloud space you have available. Buy more iCloud storage - Apple Support) or an off-device storage service such as DropBox.

Use the Files app on your iPhone, iPad, and iPod touch - Apple Support

Cheers.

Hello agnieszkaAgga and welcome to Apple Support Communities.

I see you're trying to move a video shot on your iPhone 11 Pro to your computer, but the file isn't being displayed for you to import to your computer via USB.

This is expected behavior when using iCloud Photos with Optimize Storage enabled. To import photos and videos via USB when using iCloud Photos, the photos and videos will need to be downloaded to your iPhone before you're able to import the items. To download the video to your iPhone, you can open the video in Photos, then tap Edit.

Alternatively, you can turn on Download and Keep Originals within the Photos settings for all of your photos and videos to download for you to import via USB. You can see those steps in the following article: Archive or make copies of the information you store in iCloud - Apple Support

Within the article, you'll also see how you can download the video from iCloud.com, and steps for using iCloud Photos to make your photos and videos available automatically on your computer:

"If you enabled iCloud Photos, your photos and videos are automatically uploaded to iCloud at full resolution. You can make copies of your photos and videos when you follow these steps:

• On your iPhone, iPad, or iPod touch with iOS 10.3 or later, or iPadOS, tap Settings > [your name] > iCloud > Photos. Then select Download and Keep Originals and import the photos to your computer. 
• On your Mac with OS X Yosemite 10.10.3 or later, open the Photos app. Choose File > Export.
• On your PC, set up iCloud for Windows and turn on iCloud Photos.

If you want to download a few photos or videos, use iCloud.com to download the most recent version of photos and videos. Just go to iCloud.com and open the Photos app. Then select the photos and videos you want to download and click Download."

Cheers.

Hi agnieszkaAgga.

Please reach out to Apple Support for additional options.

Contact - Official Apple Support

Cheers.