However, I use bookmarks extensively and I've noticed that bookmarks with just a number as a name will not display in the browser. Here's an example:

I have 60 playlists on Music.Youtube that I have bookmarked as simply 01, 02, 03, etc. and I have them bunched into groups of 10. This first pic shows the folders in the bookmark editor. You can see the folders on the right and the first folder is opened below showing lists 1 thru 10.

Here's what it looks like in the browser.

If I change one of the number labels to alpha, they display properly so it has to do with using numbers as names.