Okay, having watched this video, there are a few things that you are doing that are very easy to fix that will improve your serve and receive game dramatically.
It is not so much footwork that is your biggest problem, but preparation. When you serve, you are standing there watching your serve, you end up in a neutral position and you are not ready for the ball coming back. The neutral position you stand in is with your feet almost parallel to the table. It is sort of like you are hoping it goes to your backhand and you are not ready for your backhand anyway. And you are turned in a way that, if the ball goes to your forehand, you cannot hit a good one, you are forced to hit the forehand with your body too parallel to the table so, it ends up being all arm with no body behind it.
One thing you want to do is focus on getting into a ready position as quickly after you serve as possible. You want to be ready, before your serve bounces on your opponent's side if the table, so you can see what your opponent is going to do with the ball and react to it. Right now you are trying to react to what your opponent does with the ball while you are not ready for it to go anywhere. You do a good job of reacting based on that fact. But you need to get ready much quicker.
In my opinion, unless you are preparing for a specific backhand shot that you are willing to move anywhere on the table to hit (the way Zhang Jike does, and I don't recommend this unless you are really good at it and have an idea of what is going to come at you), so my recommendation is that, after you serve, you set up for a forehand, from about where you were serving but a little further back. Why? If you are set for the forehand and need to switch to your backhand, it is an easy shift of your racket and your upper body. You don't have to change your feet very much. Also, most players can cover at least three quarters of the table with their forehand if they simply think about it. If you are set for your backhand, and it comes to your forehand, you are in more trouble because it is hard to move for a backhand on the forehand side, and it is a big shift to open your hips and stance for the forehand.
If you are set for your forehand before your opponent receives your serve, you should be able to receive the ball anywhere on the table. You can watch your opponent, this is pretty much what he is doing.
The next thing that you are doing is very related. When you are receiving serve, you are standing with your feet almost parallel to the table, as though you want to be ready for your backhand, but you are not fully ready for your backhand and you seem to thinking, "but what if it comes to my forehand." The end result, again, is that you are not fully ready for either before your opponent serves and then when he serves, you are not 100% ready for the backhand when it comes there, and you are not able to turn open to your forehand when it goes to your forehand. Look at how your opponent receives serve. His feet are fully open, ready for the forehand and when it comes to his backhand he just turns to it. Here again, unless you have really good footwork and could move, to a place deep and short on the forehand side, receive the serve with your backhand and then get back into position for your backhand (like Zhang Jike)--unless you are able to do that really well--you probably want to start with your feet open for the forehand and ready for the forehand, while at the same time, prepared to turn to you backhand as soon as you know the ball is going there.
What I would actually do is look at the way a few pros prepare to receive serve and imitate that. And look at the way those same prose get ready for the return right after they serve and imitate that.
It is definitely easier to move forward for the short balls than it is to move back if you get caught too close to the table and a long ball comes at you. After you serve you might want to create a little distance between you and the table and open for your forehand while being ready to receive on either side.
What I am talking about will take some practice and some hard work to change. It will feel strange at first to set yourself up differently for receiving serves. But how you are receiving serves and how you are getting ready for the return after your serves will not work against a decent player, even if you can get away with it against someone who has trouble with your serves or does not set themselves up well for their own serves. A good tactical player would really just pick you apart with how you are standing to receive serves and how you are getting ready after your own serves.
The good news is your fundamentals, your strokes and footwork are pretty decent. Everyone can improve but you are at a good place to improve from.
The biggest issue I saw in your rallying skills was similar to what I already said. Once you hit the ball you need to get ready for the next shot faster and you have to get ready for something (either forehand or backhand; I still recommend forehand for the same reasons, plus, your forehand is pretty good).
After your strokes you come to a place where your feet are almost parallel to the table and you are not quite ready for either the forehand or the backhand.
I guess the thing that everyone seems to need to work on is bending the knees, staying low and keeping your weight forward and on your toes.
But if you start with changing how you get ready after your serve and how you start when you are waiting to receive serve, these two things will help your game play improve fairly noticeably.
