I assume you mean in regards to cryptocurrency. Basically, you setup a movie streaming site full of the latests blockbusters, make it all pretty and what not and then set up javascript miner to be installed/ran on a potential viewers computer.
Basically, you'll configure it to mine a particular cluster or node on the block chain, so lets say bitcoin, and it'll use the viewers computer/resources to mine it whilst he watched the movie or stays on your website. Since the miner is tied to your mining account (for which ever provider you have) the coins get deposited into your account.
Do note that the javascript miner does get detected by antiviruses as malicious. So be warned.
TL;DR It's when you setup an in browser miner on a movie streaming site to mine a crpytocurrency using a viewers computer's resources.