Quicktime files won't open after being copied to USB stick

Hello graybrown,

Did you make sure that the USB stick was formatted correctly for files coming from the Mac? If you're unsure, this guide will cover how to do so: Erase and reformat a storage device in Disk Utility on Mac - Apple Support.

1. If you have any files you want to save, copy them to another storage device.

2. Open the Disk Utility app  on your Mac using one of the following methods, depending on the type of disk or volume you want to erase:

- If you want to erase your startup disk: Start up your computer in macOS Recovery, then choose Disk Utility in the Recovery app. To learn how to start up your computer in macOS Recovery, see Intro to macOS Recovery.

Note: If you want to get your Mac ready to trade in, sell, or give away, and your computer is a Mac with Apple silicon or an Intel-based Mac with an Apple T2 Security Chip, use Erase Assistant.

- If you want to erase any other type of storage device: Double-click Disk Utility in the /Applications/Utilities folder.

3. Choose View > Show All Devices.

4. In the sidebar, select the storage device you want to erase, then click the Erase button .

5. Click the Scheme pop-up menu, then choose GUID Partition Map.

If the Scheme pop-up menu isn’t available, make sure you selected the storage device you want to erase—it’s at the top of the hierarchy.

6. Click the Format pop-up menu, then choose a file system format.

7. Enter a name.

8. (Optional) If available, click Security Options, use the slider to choose how many times to write over the erased data, then click OK.

Secure erase options are available only for some types of storage devices. If the Security Options button is not available, Disk Utility cannot perform a secure erase on the storage device.

9. Click Erase, then click Done.

Kind regards!

Hello graybrown,

There could be an issue with the thumb drive itself since those same files open as expected on a different drive. You may want to use Disk Utility to repair the drive to see if that helps: Repair a storage device in Disk Utility on Mac - Apple Support

1. In the Disk Utility app  on your Mac, choose View > Show All Devices.

If Disk Utility isn’t open, click the Launchpad icon  in the Dock, type Disk Utility in the Search field, then click the Disk Utility icon .

Note: If you’re checking your startup disk or startup volume, restart your computer in macOS Recovery. See the Apple Support article About macOS Recovery on Intel-based Mac computers. Next, select Disk Utility in the macOS Recovery window, then click Continue. If you check your startup volume (Macintosh HD), make sure you also check your data volume (Macintosh HD - Data).

2. In the sidebar, select a volume, then click the First Aid button .

3. In the First Aid dialog, click Run, then follow the onscreen instructions.

4. When the First Aid process is complete, click Done.

5. Repeat steps 2 through 4 for each volume on the storage device.

6. In the sidebar, select a container, then click the First Aid button .

7. In the First Aid dialog, click Run, then follow the onscreen instructions.

8. When the First Aid process is complete, click Done.

9. Repeat steps 6 through 8 for each container on the storage device.

10. In the sidebar, select the storage device, then click the First Aid button .

11. In the First Aid dialog, click Run, then follow the onscreen instructions.

12. When the First Aid process is complete, click Done.

Keep us posted.

Take care!