Your general stance is to upwards/straight basically all the time. Bend your legs/knees more and lean a little more forward to actually stand on the front of your feet.

If your knees are not bend like in this picture you have no lateral movement ability and hitting the ball below your belly button is not the height you want to hit it. You want to hit it more between shoulder height and upper belly height.
You get drawn into the "old grandpa push battle" where you basically are lazy and sometimes even have your right foot planted in front and just play backhand pushes. It is easy to be lazy and to think "hey the next ball will be a push too so i stay with the right foot infront", but the real answer should be to instantly go back with that right foot so you are in a proper stance to actually loop the next ball. It is probably not intuitive at first but you really HAVE TO get out of that right leg forward stance, because otherwise no ball will feel like it is the right one to loop.
The push rallies mainly were with very low spin, where your opponent even opened up his bat so that the rubber pointed at you and lobbed the ball over which means there is actually no backspin on it. Especially in these kind of "push rallies" you can basically loop every ball at will. Now you can not play a bomba loop on these relatively empty balls, but you can at least show the initiative to put some topspin into the rally.
Gladly your opponent can't loop either, because he has a too thick ball contact and punches the ball into the net instead of actually spinning it over to you.
All of the serves i have seen so far (your's and your opponents) did have next to no spin in them. The movement was more of somebody acting as if they had seen Ma Long do a serve, but the actual contact was blunt and mostly no or topspin. Additionally these were all quite high. Some of them you could have smashed, some of them you could have looped (but not with a big move, but rather just go over the ball just using your forearm).
Professional start to the serve

Then you throw it up correctly, but hit it too high and without brushing you actually shoot the ball into the table

The serve is probably 20 or 30 cm above the net and a more seasoned player would simply smash it
As others already mentioned. Serves are the easiest to learn since you can do it alone. Try to get them low over the net first. That will be hard enough for amateurs to handle, because if you do a topspin serve that is low, the amateur response to low balls is always push which will lead to many easily smashable balls for you.
Many points i mentioned actually depend on each other. The more upright upper body posture disables you from properly reacting to the serves and loop them. I have the same problem, but perhaps i am 10 % lower and it does work and it intuitively enables you to react to the serves. The rule should be to loop every long serve.
I do have the same problem that i can get lured into the old grandpa push battles where i keep my dominant foot forward and stay planted while pushing several times. I do a deliberate reset of the stance after i notice it to be able to loop the next and usually that works.
On 05:20 you received the no spin high serve to your backhand well by simply countering it. This is of course even easier than spinning it. Well done !
On 05:43 until 05:58 you try to outlast your opponent in the grandpa pushing rally keeping your right foot in front probably simply waiting for your hair to become grey so it does match the game style

Another note on that very ball exchange is that your "backspin serve" actually has no backspin in it otherwise the opponent could not return it with such an bat angle.
Here are a few examples of a trainig match against a guy who is better than me and who often plays side-topspin serves to my backhand or wide backhand. The first times i played against him i always tried to push or chop them which basically made them go everywhere but on the table. I really had to be courages enough to spin them. Bonus of this is that i never get into the stupid old grandpa chopping duel.
(me being in the black outfit on the left)
Hope it helps to see a more amateur player show what he says than expecting you to imitate WCQ or Ma Long. If i can do it, you can too.
In my opinion you dont need any tactics to win against this player because he has nothing that would really threaten you if you just did the basics right. There is no need to powerloop him or place the ball very well. Just do a simply spinny loop and the rally is over.
The one thing that i liked was the pendulum sidespin serves of your opponent to your forehand and especially towards the end of the games you returned them quite well.