Hello Mastersoftheuniverse,
Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with watching videos on your new iPhone 12. Which exact version of iOS 15 are you updated to under Settings > General > About? If you haven't updated to iOS 15.0.1 yet, we recommend creating a backup as described here: Back up iPhone
Then, update your iOS as outlined here: Update your iPhone, iPad, or iPod touch
If the issue persists, or you've already updated, are there any updates for these apps in the App Store? This link goes over how to update your apps: How to manually update apps on your Apple device
We hope this helps.
Cheers!