From where do anime streaming sites take their videos from?

Legal streaming sites like Crunchyroll, Viz, and others get their source directly from the original distributor/publisher after they get the license/rights to stream the series.

Outside of those sites (which are considered "gray area"), they use any possible sources, from ripping the video from the original streaming services and DVD/BD to downloading from existing sources, which is basically piracy since it's a copyright infringement to distribute works without permission, regardless if they are already licensed or not yet licensed.