Youtube changes

So I was on an internet forum I frequent last night, and unsurprisingly, people made comments that involve Youtube links, as is part of the commenting culture there. Normally I can click on the links, just see the title of the video, and get the joke.

But this time, the videos autoplayed! For the longest time, I had Flash turned off so that Youtube videos wouldn't start loading by default, until I clicked and told the site too. I don't have unlimited bandwidth, so it's a way to save bandwidth. But it turned out these weren't Flash videos. These were HTML5, which is the new standard (as I understand it an official web standard since 2014, although it's been in development for years before that).

My guess, therefore, is that Youtube has completely gotten rid of the possibility of having Youtube play Flash and is pushing everybody to HTML5. Uploading videos would remain unchanged, since Flash is basically just an application for playing the videos, and this is all on Youtube's side. If you look at any of the posts where I've embedded a Youtube video, those all seem to remain the same. The point isn't to break old videos, which would be a massive inconvenience to everybody, but to change on Youtube's end the application that plays them. If you do it right, and everybody knows how website changes don't go well, it should be a seamless thing for the end-user. (Youtube, of course, has had years to work out the kinks; it's just us late adopters who see the changes now. I still use IMDb's old format for displaying pages.) But it was irritating having to find the Firefox setting to turn off autoplay.

Has anybody else noticed a change?