Because you want to punch the bag with a penetrative snap. Not a push.
You were trying to achieve the effect that other guy had on his video.
So here you are pushing the bag. Which is why it doesn't react the way you want.
Here you are no longer pushing. Because the surface is hard and you would hurt yourself.
I think the reason in my video that the bag jump more is because I punch above my forehead(punching above the silver duck tape band of the white bag) and also combining with kicking that push the bag. Also, I punch a little deeper into the bag instead of not trying to penetrate into the pole for very obvious reason!!! If I only punch to shoulder level like most of the videos, it will look a lot better. I even explained I intentionally punch into the silver duck tape(my shoulder level) at the very beginning and very end of the video to show the bag behave very different. Punching high, I cannot achieve straight in and out.
I am not saying I punch good, I explained in the post that I punch high to simulate fighting with a tall guy as I am only 5'5". Also the white bag is only 70lbs, not 100+lbs that doesn't move as much. When I punch at the silver duck tape bag doesn't move nearly as much. In most videos, people punch at shoulder level or even lower. It is SO SO SO MUCH EASIER. Try it yourself and compare punching at shoulder level vs above your forehead, you'll see the difference on how the bag moves and how much harder to punch good at higher level.
Most of the people are taller than me, I don't think they realize how hard it is to punch higher. If I have to punch to the face of the taller guy, I have to punch above my forehead level, that's the way I practice for the better or worst, this is life for me as a short guy.
Also, I think the heavy bag makes a big difference. Some bags, even though it is stiffer, it does give and you can penetrate more. Those Everlast do NOT give, it's not like a rock, but the stuffing inside really doesn't give and cushion like those boxing bags. Particular towards the bottom, it's like rock. I did stuffed both bags a little at the top portion using the old stuffings I pulled from the old heavy bag I cracked. Like the while one is about to crack any time, I am going to save the bag and use the stuffings to stuff the top portion of the new bag. This not only make the new bag harder, it also make it last longer. If you don't stuff and punch at shoulder level, the bag will crack quite fast.