I need to make a hole in a cylinder but it doesn't work my video
Update: Video try # 2
I solved it:
You are putting the modifier on the wrong object - you want to put it on the object that is getting the hole put it not on the object creating the hole. If you look at your video you can see that boolean actually did work correctly - before you deleted it you can see that the wider cylinder was subtracted from the thinner cylinder's mesh.
It should work. Put your cursor over this tab
and press Ctrl + A, which should apply it and make the boolean modifier disappear. Now when you move away the cylinder, there should be a hole in it.
Example: