Yes, that's why I mentioned Tumblr in particular. Tumblr is an example of a website where people write HTML, yet don't control the HTML that displays to others.
On sites where you control the HTML, like Wordpress, you can do whatever you like. Use <video> tags if you know them. Likewise, on sites where you don't write HTML (e.g. Facebook, as another poster mentioned), <video> tags are fine--because people don't have to know about them, so it's all just handled in the background when you drop a video on the page.
But there are these in-between web services where HTML is used, usually as one method of several, to get rich text from people, and then presented in an aggregate view (think of any traditional threaded forum.)
Because people can do some pretty nasty things when you inject their HTML directly into your pages, you have to filter that HTML to remove bad behavior. And usually <video> is one of the first to go--not because it's particularly bad (though getting people to autoload huge videos can be used as a DDoS attack in some instances) but because these filters are usually whitelist-based, and haven't been updated since <video> became a thing.
On sites where you control the HTML, like Wordpress, you can do whatever you like. Use <video> tags if you know them. Likewise, on sites where you don't write HTML (e.g. Facebook, as another poster mentioned), <video> tags are fine--because people don't have to know about them, so it's all just handled in the background when you drop a video on the page.
But there are these in-between web services where HTML is used, usually as one method of several, to get rich text from people, and then presented in an aggregate view (think of any traditional threaded forum.)
Because people can do some pretty nasty things when you inject their HTML directly into your pages, you have to filter that HTML to remove bad behavior. And usually <video> is one of the first to go--not because it's particularly bad (though getting people to autoload huge videos can be used as a DDoS attack in some instances) but because these filters are usually whitelist-based, and haven't been updated since <video> became a thing.