WebM Mediasource:

[NoScriptUser007]

In Firefox 36, I was trying out the new Webm thing that results in the use of the bandwidth VP9 codec. Noscript is showing "Mediasource:" as though it is a site, whereas I think it is something similiar to http, or https, or ftp and so forth. To repruduce, in about:config filter using "media.mediasource" and set the 4 preferences to true and try a video on Youtube.

I think the full "url" is something like mediasource:https://www.youtube.com/moregobblygook where "moregobblygook" are random characters.
I'm thinking this mediasource business is part of the Webm api.
I'd like to be able to permit "mediasource:https://www.youtube.com/"

[barbaz]

You might see if you can entering in the whitelist panel manually, but note that it used to be that mediasource: URLs were just straight GUIDs and not GUIDs prefixed by origin...

Bear in mind that mediasource: URLs are NOT like http, ftp, etc.
mediasource: URLs are all dynamically generated pointers to content dynamically generated by a site you've *already* allowed - no JS means no MSE - so how much of a security benefit would this RFE really give?

EDIT If MSE does pose additional security risk, maybe better would be to have mediasource: handled instead by Embeddings just like WebGL currently is?

[NoScriptUser007]

The point I was making is, right now, Mediasource displays as a site. But I actually got things to work. I also use an addon called RequestPolicy, and it won't handle mediasource. So I allowed Youtube in RequestPolicy and made an ABE rule to substitute for what RequestPolicy was doing and came up with this:

Site .youtube.com
Accept from .youtube.com .googlevideo.com .ytimg.com .google.com
Accept from mediasource:
Deny

For awhile the ABE text was red, but now it is black and Youtube is playing the bandwidth saving VP9.
But, that appeared to me to be a bug that "mediasource:" is treated as a site without the actual domain.

[barbaz]

It's not a bug because mediasource: URLs are just unique identifiers not something that has "domain".