Hello aknoxclark,
We see that you came to us from the article titled: If you can't watch or stream movies and TV shows in the Apple TV app - Apple Support
Be sure that you've looked at the specific section of that article that is listed below that can help with getting your content working on your Mac again.
If the movie or TV show won't start playing
After each step, try to stream or download the movie or TV show again.
1. Check the System Status page for service interruptions or check a third-party provider's website for any interruptions. If there are service interruptions, try to stream or watch the video later.
2. If you're having trouble signing in with your Apple ID, you can reset your Apple ID password or learn how to get a verification code and sign in with two-factor authentication.
3. If your cellular connection is poor, connect to Wi-Fi instead.*
4. Try watching on a different device using the same Wi-Fi or cellular connection. If it doesn't work, contact your internet service provider to see if there's an issue with your network.
5. If other people are using Apple TV+ or Apple TV channels, make sure it doesn't exceed the limits for streaming on multiple devices.
* Make sure that your Wi-Fi router is 802.11a/g/n/ac compatible. Streaming HD content requires 8 Mbit/s or faster. Slower tiers of Wi-Fi connections might not be fast enough to stream HD video content.
If there are any accessories connected to the Mac, including external displays, try temporarily disconnecting them to help rule out any possible conflicts as well.
If the movie or show is being streamed, see if downloading it to the device helps, as that can rule out connection-related issues.
If you've tried these steps and the issue remains, you'll want to reach out to Apple Support.
Get Support
Cheers.