https://lists.w3.org/Archives/Public/public-html-bugzilla/2010Apr/0042.html
[Bug 9224] It should be mentioned that setting playbackRate can be ignored. I.e. if playing...
https://developers.weixin.qq.com/miniprogram/en/dev/api/media/video/VideoContext.playbackRate.html
VideoContext.playbackRate(number rate) | Weixin public doc
the doc for Weixin develoers
numberrateweixinpublicdoc