To achieve long battery life when playing video, mobile devices must decode the video in hardware; decoding it in software uses too much power. Many of the chips used in modern mobile devices contain a decoder called H.264 – an industry standard that is used in every Blu-ray DVD player and has been adopted by Apple, Google (YouTube), Vimeo, Netflix and many other companies.
Although Flash has recently added support for H.264, the video on almost all Flash websites currently requires an older generation decoder that is not implemented in mobile chips and must be run in software. The difference is striking: on an iPhone, for example, H.264 videos play for up to 10 hours, while videos decoded in software play for less than 5 hours before the battery is fully drained.
When websites re-encode their videos using H.264, they can offer them without using Flash at all. They play perfectly in browsers like Apple's Safari and Google's Chrome without any plugins whatsoever, and look great on iPhones, iPods and iPads.
Fifth, there's Touch.
Even if iPhones, iPods and iPads ran Flash, it would not solve the problem that most Flash websites need to be rewritten to support touch-based devices.
Sixth, the most important reason.
Besides the fact that Flash is closed and proprietary, has major technical drawbacks, and doesn't support touch based devices, there is an even more important reason we do not allow Flash on iPhones, iPods and iPads. We have discussed the downsides of using Flash to play video and interactive content from websites, but Adobe also wants developers to adopt Flash to create apps that run on our mobile devices. We know from painful experience that letting a third party layer of software come between the platform and the developer ultimately results in sub-standard apps and hinders the enhancement and progress of the platform. If developers grow dependent on third party development libraries and tools, they can only take advantage of platform enhancements if and when the third party chooses to adopt the new features. We cannot be at the mercy of a third party deciding if and when they will make our enhancements available to our developers.
This becomes even worse if the third party is supplying a cross platform development tool. The third party may not adopt enhancements from one platform unless they are available on all of their supported platforms. Hence developers only have access to the lowest common denominator set of features. Again, we cannot accept an outcome where developers are blocked from using our innovations and enhancements because they are not available on our competitor's platforms.