I know all of the PPC users are using TenFourFox, as it's the only browser still updated. But there's another good option: Camino (caminobrowser.org). It hasn't been updated since 2012, but I find that it works fine with most websites. And it fast, especially on a G5. It totally beats TenFourFox in speed. And YouTube. Camino can play YouTube using Flash, and as much as I hate Flash Player, I think it's better than HTML5 for watching YouTube on PowerPC. It plays great with 360p, even on my 1.33GHz G4 (I'll test my 700MHz later). I can watch 720p smoothly using my Dual 2GHz G5, and 1080p will sort of play. It skips a lot but gets better as the video plays. I imagine that you might even be able to watch 4K on a G5 Quad. Just thought I'd let everyone know that Camino is sill a great alternative to TenFourFox if you need speed over compatibility. I'm typing this in Camino now. I hope you try it!