Good news everyone! I've devised a new YouTube browser very similar to TenFiveTube called SurfTube, which is essentially just the Surf browser specially configured for YouTube usage, then packaged into a graphically launchable format. TenFiveTube has met its match; but unlike TenFiveTube, SurfTube on a 2GHz G5 can stream 720p HD video flawlessly in full screen (below image is not the full screen). Installers for Ubuntu 14.04+ and Debian 8+ are available in The PowerPC Linux Wiki under the Software sector. Give it a shot, even on Intel!