You generally cannot legally or reliably screenshare Netflix on Discord because Netflix uses DRM/protected playback
If you try, Discord may show a black screen or no video
Make sure you have the right to share the content and follow Netflix’s terms of use and copyright rules
Use Netflix Party/Teleparty or a similar watch-party service instead
If you are sharing your own non-protected content, open Discord and join a voice channel
Click the screen share button
Select the application or screen you want to share
Turn off hardware acceleration in your browser or app if you get a black screen
Use a browser window rather than full-screen mode if needed
Update Discord, your browser, and graphics drivers
Restart Discord and try again if the stream does not work