The distinction between downloading and streaming can be considered odd from a technical standpoint, however I do think that it's much much easier to stream illegal content unknowingly than it is downloading it.

Basically, if you download an episode of a TV show for free, common sense would tend to say that something is fishy: you end up with a file on your drive forever. However, in the case of streaming, I feel like it's much less clear.

Two scenarios: I want to watch an episode of The Office, I google "The Office season 6 episode 3" and end up watching the episode with ads on Hulu. I can also pay a subscription to watch any episode I want.

I then want to watch an episode of Dexter and google "Dexter season 5 episode 3" and end up watching the episode on MegaVideo with ads (for MegaVideo, MegaUploader… mostly) and a daily limit that can be waived with a subscription.

The first one is legal, the second one is not but a non-savvy user couldn't really tell the difference. I don't really have a way to know that MegaVideo doesn't pay the copyright holders with the subscriptions and ads.