I recorded high quality video files on my iPhone XS Plus -- 4K at 24fps.
I moved these files over from my phone via two methods: via Image Capture onto my iMac and via Dropbox uploads. My mac will not open these files in quicktime despite them being .mov files. iMovie also refuses to open these files.
I don't understand how I am supposed to view these videos once they leave my phone.
iPhone XS Max, iOS 12
It may depend on the OS version of the Mac, and some other settings:
Using HEIF or HEVC media on Apple devices - Apple Support
Macs with macOS High Sierra 10.13 or later, should be able to handle HEVC (H.265) media.
Macs with macOS Sierra 10.12 or earlier, should be able to have HEVC (H.265) media converted to AVC (H.264) automatically on transfer, with the right settings.
To make future recordings in AVC (H.264) instead of HEVC (H.265), change on your iPhone: Settings﹥Camera﹥Formats﹥Most Compatible.
To convert HEVC (H.265) to AVC (H.264) on transfer (e.g. Image Capture), change on iPhone: Settings﹥Photos﹥Transfer to Mac or PC﹥Automatic (Yes: this setting is also for video!) [The other setting, Keep Originals, transfers the file in the native format, without conversion.]
It may depend on the OS version of the Mac, and some other settings:
Using HEIF or HEVC media on Apple devices - Apple Support
Macs with macOS High Sierra 10.13 or later, should be able to handle HEVC (H.265) media.
Macs with macOS Sierra 10.12 or earlier, should be able to have HEVC (H.265) media converted to AVC (H.264) automatically on transfer, with the right settings.
To make future recordings in AVC (H.264) instead of HEVC (H.265), change on your iPhone: Settings﹥Camera﹥Formats﹥Most Compatible.
To convert HEVC (H.265) to AVC (H.264) on transfer (e.g. Image Capture), change on iPhone: Settings﹥Photos﹥Transfer to Mac or PC﹥Automatic (Yes: this setting is also for video!) [The other setting, Keep Originals, transfers the file in the native format, without conversion.]
Quicktime won't open .mov files created by iPhone XS Plus at 4K
