I have a question for article writing: how do I post a video from YouTube video into my article?

Same way you do in the forum:
Click the <> Show Source button. All other buttons will become disabled. Paste the embed code of the video. Click the <> button again (now it's called Show Rich Text) and the video should appear inline.

shakin steak wrote :

Same way you do in the forum:
Click the <> Show Source button. All other buttons will become disabled. Paste the embed code of the video. Click the <> button again (now it's called Show Rich Text) and the video should appear inline.
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Yup. What he said. Soon I will be having Moudy and team working on an easier way to post videos.