You can see examples of the type of stuff the steem blockchain holds here:

https://steemblockexplorer.com/block/26378428

and you can see raw transaction data related to transactions verified in a given block by choosing the link to the transaction id for any of the multiple transactions occurring on that page! :)

You could store bytecode, for example, on the steem blockchain if you wanted to, and that bytecode could be representative of video data, etc.; now, it is at a DApps discretion what they try to upload/what they do upload and how they divide resources, but the possibilities of what you store on the blockchain are limitless (with an associated cost, of course).