Quicktime only plays audio with dash cam micro card

What movie codec and details does the movie have? You can check them with MediaInfo or Invisor.

For example: H.265 Codec ID hev1 has an error message "This file contains some media that isn't compatible with QuickTime Player" and plays audio only. There is a lossless fix if you install ffmpeg and add '-tag:v hvc1' without re-encoding in the Terminal:

ffmpeg -i input.mp4 -c copy -tag:v hvc1 output.mp4

An easy workaround is to play such movie with IINA.

https://iina.io

Verify that your downloaded file is 84,692,284 bytes in size, to make sure the download was complete.

macOS should use Disk Image Mounter to open a .dmg file; part of macOS itself. Not sure how that wouldn’t be available to all users?

Tom Perkins1 wrote:

iina but got the following screen shot

weird. Just tried and that .dmg opens OK for me.