When AFTER EFFECTS opens with your video loaded, go to EFFECTS & PRESETS>, select REMOVE GRAIN and drag it onto the timeline for your video.Right-click, the timeline for the noisy video, is PREMIERE PRO, and click REPLACE WITH AFTER EFFECTS COMPOSITION.In this case, you could open your video in ADOBE AFTER EFFECTS using the following steps: This is because while the masks are static, the contents of the video are not. Even when the MEDIAN effect is applied with masks, you may find that the denoising effect is applied to parts of the video where noise reduction is not needed.
Noise reduction in Premiere Pro does not always yield the best results.
Part 1: How to Reduce Noise in Premiere Pro