Your video is very fast and hard to follow especially given the unfamiliar language. But it appears you inserted an assembly copy. Why? Just open a new assembly with the chair as a subassembly. Change the occ prop user defined qty of that chair subassembly ONLY to 50 or whatever.
If you want a note separate from the BOM you will have to do it manually. If you do it the way @Trikefreak and I suggest you will get the chair assembly as the first item in the BOM but the quantity you put in occurrence props on the chair assembly only will multiply the chair and all its parts and show the needed quantity for all the parts in the BOM.
It won't be a note separate from the BOM but it will be automatic.
Create new assembly, drop your chair in there, set the occurances to 10. You know how to do this? Right click over the assembly in your file tree, occurance properties, set user defined to yes, then put 10 in the quantity.
When you put your bom list on your drawing, choose atomic list, and it will "fingers crossed" do what you are wanting.
I have many drawings made, linked to the assemblies, that must be edited.
I know how to link it with another, but it's a lot of work.
The external note is manual, I do not need it automatically.
I wish there is a box where you can edit the number of assemblies, and multiply the number of pieces. But no exist.
Dreaming costs nothing
I will continue editing manually.
thank you very much