iphone 12pmax HD60 video not playing back on Mac iphoto.

I suppose you mean Photos. iPhoto has been replaced by Photos years ago.

You need to tell us specifically the video settings, and also how you are importing your videos to your mac.

Try opening one those videos with Quicktime Player. Does it play?

Press command-I and twirl open the video settings. Post a screenshot.

Hi Sailor666666,

You've let us know that when using iPhoto, you're unable to open specific videos due to a 'Format not supported' error.

Can you tell us which version of macOS we're working with? Are you using iCloud or transferring your videos by connecting your iPhone to your Mac? Is this happening with all videos? Last question, is this happening with the same video in other apps like iMovie, QuickTime, etc?

We look forward to hearing back with these details!

Change the format for the camera to "Most Compatible" in Settings on the iPhone.

The machine you are trying to view the format must support the file format.