Copied from here, as I didn't see we had a Tech Support forum up:

Have any of you guys tried watching someone else play Homeworld Remastered using Steam broadcast? Do you get weird audio and a green screen? If not, could you try watching someone?

I've never had this issue before so I'm assuming it's the game and not an issue my end, but if others can confirm the problem then I'll report it on the Gearbox forums (if it's not already).