Suddenly can't screen share Netflix or Amazon Prime

Sounds like it could be HDCP.  Being on a Mac, not sure if there's much you can do.

I had the same problem. Go to Chrome (three dots in upper right), Settings, Advanced, System, Turn off "Use hardware acceleration."

this worked for me.

It might be because of the DRM protection. You can try to download the videos using a third-party downloader tool like Tunelf, then share the local video files. 

Apart from disabling hardware acceleration on your browser, you can also customize Zoom settings: 

Settings > Video > Advanced, and disable all options under the "Use hardware acceleration for" section

Screen Share > Advanced and turn off all options under the "Use hardware acceleration for" section.

If there is still a problem, you can use StreamUlt to screen share local Netflix files on your Zoom.