Are you sure you're using Theora 1.1 (aka Thusnelda)? Version 1.1 might be consider "inefficient" but 1.0 was simply "broken" for many uses.<p>You mention Macs and I'm not sure if there's been an official 1.1 release of the XiphQT Quicktime plugin yet, which would affect you if you're using Mac tools to generate the video.<p>Also, does Perian play Theora now? I'm guessing you meant the XiphQT plugin which enables Safari support.