Post Effect on video player with render mode - Render Texture

I am displaying some videos using Unity Video Player.

Render mode is set to a Render Texture.

I want to apply a simple post effect (it's for mobile) for a specific period of time on the video over the Render Texture. Video is displayed only on 30% of the screen while other areas are UI elements.

I saw Post-processing Stack v2: https://github.com/Unity-Technologies/PostProcessing
How do i apply post effect only over a specific Render Texture of the video player?