The problem is generally video rendering settings on certain browsers.
Try using a different browser. Firefox video settings should work by default.
If you are using Google chrome you can disable hardware acceleration by :
1. Going to settings in the browser. You can find this setting by clicking on the three vertical dots under the "X" that closes the browser.
2. In setting search for "hardware acceleration"
3. Un-check the "Use hardware acceleration when available" and then click the "re launch."
With one of the two solutions above students/meeting participants should now be able to see video from streaming services when sharing your screen on zoom.