how do I upload videos to iCloud photos?

I have converted some old videos to the MP4 (standard and H264 versions) to try to upload them from my PC into my photos, so they will move onto my iPhone 6.

Last week I managed to do this by logging in to icloud on my browser, then dragging and dropping into the photo library. However I'm trying it again now with more videos and it's saying that it only supports JPEG files.

When I move to the videos section in the browser, there isn't an upload functionality.

I've managed to upload them to iCloud Drive, but this doesn't let me see them on the iPhone.

Is there still a way to do this?