RE: 'It's Happening!': the Purge
Well, just the same way one adds archival material to archive.is: just add it to the URL. Once the data is sent to the blockchain, it is incorporated into blocks. Screenshots, videos, websites, all of it. Distributed nodes then preserve the data in the blocks in decentralized copies--out of reach of censors (unless they can take down 34% of the blockchain with a firewall attack, or 51% through traditional Sybil attack).
There may be some ways to incorporate archival material to extant blockchains. Like I said, I dunno. I do know that there is material encrypted in the BTC blockchain, for example.
What I do know is that if we don't start archiving history as it happens, the erasure of proof of crimes is going to continue, and will get worse.
I don't know if you can archive video that way, DTube for example uses IPFS. EOS is supposed to incorporate IPFS for file storage, perhaps it would be easier to build an archive there. Having said that I seem to recall @dan talk about the block producers being able to take down "objectionable" content, this makes sense from a child porn type angle but if the authorities bring pressure to bear on the block producers for political reasons, you could end up in a similar boat to them bringing pressure to bear on the wayback machine operators I suppose. It's worth thinking about though.
So basically include any and all links, on any posts?
To archive a site you run across on the internet on archive.is, you add /archive.is to the url of the site. If the site is already archived there, you'll find it there. If it isn't, you just added it.
But, yeah, include links in your posts =)