Well that's the thing, witnesses are about making sure the blocks of records are correct. Their data is essentially what we can view on an explorer. Very raw data. That's my understanding.

Images and Video though can't be stored on Blockchain. This is what has always existed as one big reason why Blockchain can't scale well. Transactions of meta data is one thing. Bandwidth like streaming video is another thing. I'm not really sure how it all works but I remember when I did some research on steemit it was utilising AWS as the content storage servers.

So this really means that Blockchain isn't truly decentralised and it's why it can't just take over regular internet like many claim or hope.