Hello Yikyikhuoyik,
Thank you for using Apple Support Communities. We'd like to help you with this Safari issue you're experiencing by recommending some troubleshooting steps you can attempt. Follow the steps below:
1.) If Safari isn't properly working while watching videos, then review and attempt the troubleshooting steps listed here: If Safari isn't loading websites or quits on your iPhone, iPad, or iPod touch - Apple Support
2.) Also, if you have any pending updates available, please install them. This can usually help with unique issues, since updates include fixes. Just in case, this link can guide you through the update process: Update your iPhone or iPad - Apple Support
1.)Back up your device using iCloud or your computer.
2.)Plug your device into power and connect to the internet with Wi-Fi.
3.)Go to Settings > General, then tap Software Update.
4.) If you see more than one software update option available, choose the one that you want to install.
5.) Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do: If you forgot your iPhone passcode - Apple Support
We hope these steps help you. Thank you for using Apple Support Communities. Take care.