The following methods can be adopted:

On WeChat, click "Discover" - "Moments", after entering, click the camera icon in the upper right corner, and select "Small Video" in the pop-up menu.

At this time, you can use other computers or mobile phones to play music, and then press and hold the video in WeChat until the green line disappears, that is, the video is finished and then let go.

The video is finished. After letting go, enter the publishing interface and click Send to see it in the Moments updates.