Re: VinceH
Firefox - and yes, I have Javascript disabled. (I have it allowed by default on some sites, and on others I temporarily allow it as seems necessary/if I feel trusting enough.)
archive.org's scripts were allowed - that was enough to allow them to play on archive.org.
theregister.co.uk is allowed by default.
twitter.com and twimg.com are allowed by default.
No embedded games appeared either here or on Twitter - as I said, just links to the game's page on archive.org
However, in the interests of science, I have now allowed all scripts to run (and I've paused Ghostery's blocking, in case that was a factor)
The page took a lot longer to load than before, and no longer scrolls smoothly - and there are still no embedded games, only links to the page on archive.org
And again, looking at the tweets on Twitter itself (logged in or not) and they still only contain the link, with no embedded game.
Running through the config, I can't see anything obvious that I've set that would be blocking the games when embedded (or from being embedded).
I've now also loaded the page into Internet Explorer and Chrome - still no embedded games, only links (and nothing's disabled or blocked on those because I don't normally use them in anger, only for testing my own pages), and the same in both browsers when looking at the tweets on Twitter.
I won't bother trying NetSurf! ;)