When I enable the recordable window, the censored effets showing on my screen keeps flashing. How do I record a censored video propoerly? Thank you!

If you are recording your screen with OBS, once you added the recordable window as a source, you can click Hide the window  (next to create recordable window) so it will stop flashing.

Note that you can turn set the Screen latency to correct delay to 1, so the recordable window also contains your screen.