This is a little confusing. we should probably have a little description on the add from scrapbook interface. It's pretty simple though. the new copy is like doing a copy and paste: you can make any changes to the copy without effecting the original. The alias is like using a pointer, when you can place aliases all over your site (your header nav or footer text for instance), and then you just have to change it once in the scrapbook to change it everywhere else an alias has been created. So you probably want to be using the alias option.

Sorry to come back so late on this, but I'm just starting to try and make more use of the scrapbook. Understand the alias vs copy explanation but, you mention on the "add from" inteface, but thats not where it appears. It only appears on the add TO interface. Currently I have 2 scrapbooks, Admins personal and the Global one. I can't find any help information as to their advantages etc, but in the dashboard the admin one can only have items deleted from it, even when logged in as admin. The global allows me full access. The ONLY time it seems you can create an alias is when the original block is located in a page. So the scenario I fear is this:
I create a custom slideshow on a page, I then copy an alias to the global scrapbook(the only way to get an alias), I then copy the alias to the default page type and update lots of child pages. So when I change the images on the original page the effect is seen on all pages. But, equally,if I delete it from the original page it vanishes from everywhere. Have I got that right? Personally I'd like to see the original on the scrapbook and aliased to elsewhere. Its still possible to delete the original but it just seems to make more sense. If I've got this wrong and there is something written please just point me, very happy to read up. I still love this product by the way, just having the odd little issue here and there, but had lots of great help.

I just tested this to be sure. I have a block that I created on my home page and that I copied to the Global Scrapbook as an alias. I later went and applied that block to all of my pages. To test your scenario, I just now deleted the block from my home page. The block did NOT disappear from the other pages. So, and this is the way I expected them to work, aliased blocks work like hard links on Unix or references in many systems. There is no master copy that is owned by the page or the scrapbook. There is just one original copy owned, per se, by the database and all aliases including the first refer to that original whether it was created on a specific page or in a scrapbook.

I'm actually going to retract what I said. I was doing more testing and I don't think it works that way. I edited the version in my scrapbook and none of the child pages that I had previously copied to block to updated. That suggests to me that all of the pages have a full copy of the block.
Furthermore, after I edited the block in my scrapbook and reapplied it to all of my pages a new (second) copy of the block appeared on each page. That second copy does function like an alias. Edits to the block carry through to all pages. This is a rather serious bug if true. And it's not the first bug I've run into in trying to use the global scrapbook...

I think I should retract my retraction and then just shut up. :-) After still more testing it's possible the block I referred to in my first retraction was a copy and not an alias. Which would make sense. If anything is certain about this, though, it's that I need to do more testing...

It would be nice if when you went to the scrapbook if it told you whether a block was a copy or an alias...

Thanks for responding. Thank god, I thought it was me, perhaps I can cut back on the pills now. I got into a real mix about 10 days ago and didn't have time to take logical steps before I had to present a prototype. There's either something wrong I think, or it simply needs a better/fuller explanation. I love the theory but the reality tried to bite my arm off. That said of course I was still able to work round etc. Still can't really see why you would ever want to use the Admins scrapbook since once a block is there its fixed?