No special trick, you just need to use the Video Settings features to align the position, crop, and scale of the video with the app keyboard as much as possible. Once you increase the opacity to 100, it will completely replace the in-app keyboard, and it should be fine if it doesn't match exactly.
No special trick, you just need to use the Video Settings features to align the position, crop, and scale of the video with the app keyboard as much as possible. Once you increase the opacity to 100, it will completely replace the in-app keyboard, and it should be fine if it doesn't match exactly.