Question about Addtype webm


The first time I uploaded video, I religiously followed some instructions and added ‘Addtype’ statements for mp4 and webm to a .htaccess file.

That was ages ago, and since then I forgot all about that and have been uploading video to various other websites, and they are working fine without any Addtype statements. Now I’ve suddenly remembered about ‘Addtype’ and I’m wondering why my websites are working without.

So I thought that maybe Dreamhost is declaring some ‘Addtype’ statements automatically, and I found the wiki page,

which suggests that yes, Dreamhost is automatically declaring mp4. But that wiki page does not mention webm.

So my questions are:

(1) is Dreamhost also automatically declaring webm (and the wiki page should be updated)?
(2) if not, how come my sites are working without an Addtype for webm?