Quicktime won't load my videos

Quicktime is pretty picky about the formats it will open, and even about some of the coding used for the tracks inside an acceptable format. I don't think it will open MKV, for example, and not AVI.

My suggestion is to use VLC instead. It will play just about anything (and is free).

https://www.videolan.org/vlc/

VLC just doesn't have the editing features of Quicktime.

Hi ChooNBella

Thank you for your post, and welcome to this Apple (user-to-user) Community

Re: "Quicktime won't load my videos .....wheel just spins"

There are various reasons that could cause the issue you are having. We don't have much info. to go on.

Eg: Just a few examples:

(1) MacOS version isn't up-to-date - or -

(2) videos are in a format QuickTime can't open - or -

(3) interference from third-party (non-Apple) software, (eg: Virus checkers, ad-blockers, cleaners, VPN, etc). - or

(4) Your iMac may have inadequate memory / storage space available for smooth operation of all you ask of it. (Eg: At least 50 Gb free : try checking via Apple menu > System Settings > General > Storage

________________________________________________

Re: (1)

It seems you are using MacOS 15.1, on your iMac. Your MacOS version may need updating to a newer version ie: There are often bug-fixes, security updates, and more, in recent versions.

__________

Please note: It is always wise to back-up your Mac before updating or upgrading it's MacOS version

You can check for updates via Apple menu > System Settings > General > Software updates.

For more details:

Eg: For a newer MacOS 15 version : See: What's new in the updates for macOS Sequoia 15 - Apple Support

or

If your iMac model permits an upgrade: See: What's new in the updates for macOS Tahoe 26 - Apple Support

All the best :-)