How to dig out the content from a video is to dig out the portrait of the video and put it in other backgrounds.

Install a beauty album on your mobile phone and use its video keying function to make it. Even if your shooting background is not a green screen, but a real life background, you can pull out the beauty album with one click, which is much better than PR AE professional software. If your background is not a green screen, you have to dig frame by frame, which is really a waste of time and has a high threshold for use. If you don't learn, you can't, so I recommend you to use the beauty album, as long as you have played it.