YouTube just gave its users a direct line to the recommendation machine. Type a sentence. Get a feed. The video platform rolled out an experimental feature this week that lets signed-in viewers in the United States build a personalized video stream using plain English prompts. The tool appears as a “Your custom feed” chip at the top of the homepage on both mobile and desktop. Tap it and a text box opens. Suggested prompts sit below. Or write your own. “Help me unwind after work with guided meditations under 10 minutes,” reads one official example from YouTube’s help center . Another might seek “deep-dive tech podcasts about AI.” Hit enter. The page refreshes with a tailored selection of videos. And it stays pinned for easy return. But only for 30 days of activity. Prompts expire after a month of neglect. One custom feed exists at a time. Change the text box at the top and the entire stream updates. Some videos linger. Others vanish. Refreshing works much like the standard home page.…