Open X on your phone and hit a video. It fills the screen. There's no chrome around it, no address bar, no sidebar — just the video, and a flick of your thumb to get to the next one. That's not an accident. It's the entire interface, tuned over years, to remove every bit of friction between "see something" and "see the next thing."
Open the same site on your desktop and click the same kind of video. You get an inline player, sitting inside a feed, sitting inside a browser tab, sitting inside a window you can see the edges of. To get to the next video you have to move your mouse, find it in the feed, and click again. Every one of those steps is friction the mobile app doesn't have.
This isn't a complaint about desktop browsers being worse. It's that they were built for a completely different job — reading, clicking between many things, working across tabs. A video feed asks for the opposite: one thing, full attention, minimal input between posts. Nobody designed the desktop browsing experience around that use case, because until short-form video took over, there wasn't really a "that use case" to design for.
The gap isn't that desktop can't do full-screen video. It's that nothing wires "click a post" to "full-screen, swipeable, still-connected-to-the-real-feed" the way a native app does.
Why "just make the window bigger" doesn't work
The obvious fix looks simple: resize your browser, zoom in, maybe use a "reader mode" extension. None of it gets you what the phone gives you, because the problem isn't screen space — it's that the video is still living inside the feed's layout. You're still scrolling past text, avatars, and reply counts to get from one video to the next.
The other obvious fix — copy the video URL and open it in a bigger player — breaks the parts that make a feed a feed. You lose the like button, the reply thread, the account name, the ability to just move to the next post. You've traded the clutter for isolation.
What Doomly actually changes
Doomly doesn't rebuild X's player or copy the video somewhere else — both of those break on anything even slightly non-standard (long videos, live streams, weird aspect ratios). Instead, when you click a post, it takes the real media element that's already on the page and promotes it into a full-screen stage, while your actual feed keeps scrolling in the background so X keeps loading more posts the normal way.
The result is the thing the phone already does well: click once, get full-screen, keep scrolling, never lose the actions. It's not a new experience — it's the same one your phone already gives you, applied to the screen you're already sitting in front of.