I used OBS (Open Broadcasting Software) for Twitch and loved it but I think when Amazon acquired Twitch TV, some change occurred and I'm no longer able to do direct capture from games via OBS. I can only do a "Windows capture," which doesn't sound like a big change but simply doesn't seem to work as fast or conveniently, and I'd rather not accidentally share views of my desktop, as happens when you're alt-tabbing out of a game back to Steam or your desktop (if you're direct capturing the game, you're just seeing the view inside your game period).
I searched for a solution but to date haven't found any.
I don't really understand what happened, and am unsure if Amazon changed something in how Twitch interacts with OBS, or what.
Before that -- and maybe now too -- I used unregistered FRAPS. This limits you to 30 seconds I believe. While that seems short it does help prevent accidentally devouring all of one's hard drive space with one video. And it tended to sort of inspire me to edit together 30 second snippets via Windows Movie Maker to share as "compilation" videos on YouTube.
The time limit kind of forced me to look for opportunities to record something concise and special (say, a Soul Jar event in Diablo III), rather than "hey let's record on Twitch for 3 hours and then let's go back and trawl through it for interesting snippets." Actually I enjoyed both things but whatever happened to OBS in my situation has made it less of my go-to now.