Believe me, I looked everywhere for this and couldn't find a duplicate.
When you try to lock a hopper only using a redstone torch or a redstone block, it won't work. If you try straight redstone dust pointing to the hopper however, it does lock. This only works with straight redstone dust, if you try to lock a hopper any other way it won't lock.
Looking at past videos and pictures, this is not an attended feature.
Steps to reproduce:
Place 3 hoppers, one on top of the other.
Power the middle hopper using any redstone source.
Put an item in the top hopper. Notice how the item still goes through, even if the middle hopper is powered by a redstone source, except for straight redstone dust.
What should happen:
The top hopper should always lock, no matter what's powering it.
Works As Intended or Cannot Reproduce. In your first video, the redstone block only locks the upper hopper, but the hopper underneath can still pull items from the locked hopper. In your second video, both hopper get powered by redstone so the bottom hopper is locked too. If the dirt block is replaced by something cannot transfer redstone signal (e.g. glass), items will get pulled by the bottom hopper again. Also, if you put redstone block in a hopper pipe, you will see items piling up because the locked hopper can't push items into other hoppers.