Why are my personal videos buffering?

I'm having the same problem but my icloud storage is turned off i never backup on icloud, i do the backup on itunes on my laptop so why is it happening to me ?

Greetings Laurenbarbs,

Thanks for using the Apple Support Communities!

I understand that when you play a video on your iPhone that you took, there is some delay while playing. This could be explained if you are using iCloud Photo Library with the option to Optimize Storage enabled.

If you have these featured enabled, your full resolution video is stored on iCloud and downloading from there when you play it.

When do photos and videos upload to iCloud Photo Library?

When you turn on iCloud Photo Library on your iOS device or Mac, your photos and videos will upload after you connect to the Internet with Wi-Fi and your battery is charged. You can see the status and pause the upload for one day when you follow these steps:

• On your iOS device, tap Settings > iCloud > Photos.
• On your Mac, click Photos > Preferences > iCloud.

Depending on your Internet connection speed, the time it takes for your photos and videos to appear on the Photos app on iCloud and all of your devices might vary. Make sure you turn on iCloud Photo Library on each device.

The iCloud Photo app allows you to upload JPEG photos that are less than 16GB in size.

If you turn on Optimize [device] Storage, iCloud Photo Library will automatically manage the size of your library on your device, so you can make the most of your device's storage and access more photos than ever. All of your original, full-resolution photos and videos are stored in iCloud while device-size versions are kept on your device. You can download the original photos and videos over Wi-Fi or cellular when you need them.

If you turn on Download Originals, iCloud Photo Library will keep your original, full-resolution photos and videos in iCloud and on your device. Download Originals is the default setting for iOS devices with the free 5 GB storage plan and for all Mac devices.

You need an Internet connection to access an original photo or video that’s stored only in iCloud.

iCloud Photo Library FAQ - Apple Support

Have a great day!

I am also having this issue but my internet speeds are great. Both 50mbps up and download speeds so unsure why it's an issue either. So frustrated!