HTML 5 <video> tag vs Flash video. What are the pros and cons?

Question

IMPORTANT UPDATE

This question was made over 9 years ago. It made sense then, it doesn\'t make it now. Flash is hard on its way out; sup

Answer 1

I think the large majority of these answers condense to this: Flash is engineered mostly for the mass market, so it provides the easiest way to cover the bulk of the market, but it is deficient in covering less common and emerging platforms (i.e. shaky Linux and no iPhone). This has been the story with Flash pretty much from day one. It's practically a case study of how proprietary and OS software differ (and complement each other).

On the other hand, I think most answers are seriously underplaying the codec angle. There is one primary reason why Flash video dominates the web today: it's the only way to publish a single version of a video and expect it to be viewable by more than about half your audience. Even though the video tag looks to be designed well, as far as matching up multiple source files to the user's installed codecs, it's still difficult to know how many codecs are needed to cover what percentage of an audience, and impossible to know whether people will upgrade as new codecs emerge. Flash video has more known quantities, and a reasonably good expectation of upgrades for the large bulk of the audience.

I also kind of think that the performance angle is overstated in most answers, as well. It's true that Flash uses more CPU than any other player I have, but it also starts up more quickly - by orders of magnitude. When I come across a web page with an embedded MPG, my browser is frozen for 15+ seconds while QuickTime boots, or perhaps only 5 seconds if it was already running. (Almost as bad as PDF ;) ) Obviously Flash is less efficient in some ways, but from where I stand it's more efficient in others; like any software solution tradeoffs are involved.