My photos show up in a shared album but not my videos. What do I need to do?

Bear in mind that when you share photos or videos they are converted to lower resolution versions. For videos this will take some time, plus they are large files so will take a while to upload after conversion. So it might be a while after you have shared them before they appear. You will also need to leave photos open and the mac on while this takes place.

No Idea.

Are they from an iphone12 or 13? Do you have the Dolby Vision HDR turned on. Does your mac support HDR Video?

Where is your library stored? If on an external drive, what is the format?

You could try is to restart your mac in safe mode and try to see if it works then.

If it does, then start normally and try again.

See:

Start up your Mac in safe mode – Apple Support (UK)

Yes - it takes so long. Longer videos will take longer.