I don't see how the fact that other developers aren't complaining is proof that hardware acceleration is not useful. There is a full spectrum of how much acces

I don't see how the fact that other developers aren't complaining is proof that hardware acceleration is not useful. There is a full spectrum of how much access you allow browser plugins and client-side code to features of the underlying OS and hardware. Apple has chosen a relatively conservative point along that spectrum, Microsoft chose a more aggressive one (ActiveX). There is an obvious tradeoff between capabilities/performance and security. Google, with its Native Client sandbox, static analysis tools, etc. is attempting to get the performance of ActiveX with the security of more stringent sandboxes. This is an extraordinarily difficult problem, and Apple is justified in not wanting to deal with it. However, they are not justified in saying they're not leaving performance on the table. Adobe should be able to improve H.264 decode performance without HW acceleration, but it is unclear what the upper bound is on performance when running inside the browser sandbox. Certainly it can do no better than a native app. EDIT: wmf is probably right; though there is no browser-specific sandbox that prevents third-party browsers from allowing plugins access to underlying OS APIs, such an API for HW-accelerated video decoding doesn't exist. It's unclear to me if acceleration is just not supported by the driver at all, or if the capability is only exposed via a private API, reserving it for first-party apps like Quicktime. Certainly many of the GPUs included in Apple products support hardware acceleration, so it seems to be primarily a software issue.