First of all, transactions are not lines or strings. They are just data in a specific format.
You can store any sequence of bytes (aka any data) that you want in the blockchain. However just because you can does not mean that you should. Storing your data means that thousands of nodes must also store your data, and that is a lot of disk space and computer power that needs to go towards storing your data for eternity. Storing arbitrary data on the blockchain is rude to node operators and everyone else that uses Bitcoin as you are taking up block space that could otherwise be used for actual transactions. So yes, you can store data, but you really shouldn't.
That said it all, take an example from LBRY platform, the platforms didn't store the data file(media file) on the blockchain but instead, they store the metadata of the file in the blockchain and store the data file(media file) on every node that has the data. So instead of downloading data from blockchain, the only ask for the metadata and then search every node that has the data to ask for stream it.