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

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; <video> support is ubiquitous, including mobile devices. Almost anything that Flash could do, HTML can now do too. HTML won, Flash lost. If you're pondering on how to embed video in your page, just use <video> and don't give it a second thought. This question is only preserved for historical value.

Original question

Seems like the new <video> tag is all the hype these days, especially since Firefox now supports it. News of this are popping up in blogs all over the place, and everyone seems to be excited. But what about?

As much as I searched I could not find anything that would make it better than the good old Flash video. In fact, I see only problems with it:

• It will still be some time before all the browsers start supporting it, and much more time before most people upgrade;
• Flash is available already and everyone has it;
• You can couple Flash with whatever fancy UI you want for controlling the playback. I gather that the tag will be controllable as well (via JavaScript probably), but will it be able to go fullscreen?

The only two pros for a <video> tag that I can see are:

• It is more "semantic" - which probably holds no importance to a whole lot of people, including me;
• It is not dependent on a single commercial 3rd party entity (Adobe) - which I also don't see as a compelling reason to switch, because free players and video converters are already available, and Adobe is not hindering the whole process in any way (it's not in their interests even).

So... what's the big deal?

Added:

OK, so there is one more Pro... maybe. Support for mobile devices. Hard to say though. A number of thoughts race through my head about the subject:

• How many mobile devices are actually able to decode video at a decent speed anyway, Flash or otherwise?
• How long until mainstream mobile devices get the <video> support? Even if it is available through updates, how many people actually do that?
• How many people watch videos on web pages on their mobile phones at all?

As for the semantics part - I understand that search engines might be able to detect videos better now, but... what will they do with them anyway? OK, so they know that there is a video in the page. And? They can't index a video! I'd like some more arguments here.

Added:

Just thought of another Cons. This opens up a whole new area of cross-browser incompatibility. HTML and CSS is quite messy already in this aspect. Flash at least is the same everywhere. But it's enough for at least one major browser vendor to decide against the <video> tag (can anyone say "Internet Explorer"?) and we have a nice new area of hell to explore.

Added:

A Pro just came in. More competition = more innovation. That's true. Giving Adobe more competition will probably force them to improve Flash in areas it has been lacking so far. Linux seems to be a weak spot for it, cited by many.

Imagine if there was no img tag. If you want images, you have to use a 3rd party plugin, that is really slow and has no standard way to embed it in a page. You can't easily copy images in this way, and search engines basically have no clue what if it's an image or a game or anything.

Without this, no images were available.

Then imagine that a browser was released that just let you use this fancy new img tag.

The video (and audio) tag are a logical sensible way for things to work. We shouldn't need a third party plugin to use a completely standard media format.

The biggest benefit of <video>? It's easy. Crazy easy. Ridiculously easy. Your-grandma-can-code-a-video-tag easy. <video src="myfile.ogv"></video> and you're done.

<video> also has clear benefits for your users. They get a browser-native video player, which can potentially be very efficient. They get a consistent UI that won't change from site to site. Mobile browsers that may not implement flash can still implement <video>.

The only con is a temporary one, and that is compatibility. IE8 doesn't support <video>, and it will be some time before IE9 is widely installed. As well, there's some fight over which codecs to support for the videos - Firefox, Chrome, and Opera all support both Ogg Theora and WebM, while Safari and IE are shipping H.264 (though either can support Theora/WebM with proper codecs). For now, this just means that you have to post your video in two formats and provide them both with the source element, i.e.:

<video>
  <source src='video.webm' type='video/webm'>
  <source src='video.mp4' type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"'>
</video>

To add support for IE 8 and earlier, and other downlevel clients (like older versions of FF/Safari/Opera/etc), just put your standard video embed code inside the <video> tag, below the <source> elements. If the browser supports <video>, it'll ignore the embed. If it doesn't, it'll ignore the <video> and run the embed instead.

Flash is slow and inefficient on non-Windows platforms. It has potential security flaws. It stores "flash cookies" on your computer that you don't know about. There is no flash on the iPhone and unlikely ever will be (as a result of its being proprietary and its high CPU consumption).

HTML 5: Could it kill Flash and Silverlight? is an article that might answer your question.

There are probably more reasons out there.

There are many good points here, and like a Martial Arts fighting style, each point has its thrust, and each can be defended; but each can be defeated with the proper moves.

Anyone standing on arguments about "propietary" plugins will fall quickly. Microsoft, Apple, and Adobe all bear the guilt, but that's just BUSINESS. You won't change business overnight, and each layer of complexity added by a new tag such as <video> which supports a very technical interface will result in * slightly * different implementations by each browser.

HTML 5 works now, and so does Flash. How it is implemented, the skill it requires- this defines each resource, whether it's an employee's performance, a webmaster's power, or a domain's influence.

Although I'm only 40, I began programming when orange or green monochrome monitors were the color choice, and hardware installation came with prayer books instead of instruction manuals. Maybe you could figure out AT commands for the modem when it wouldn't configure with your hardware, and 64K RAM was like, WOWWWWW!

HTML 5/Flash is a minor nuisance compared to that crap. Let's all learn how to collaborate in community toward a better resource. There is an Open Source Flash Project, it will have bugs. So will HTML 5...

Every argument here is true, but not necessarily productive. Use that energy toward a solution.