使用videojs-contrib-ads时，主要内容在video.js中预先播放之前开始播放

When using videojs-contrib-ads to create an ad plugin in video.js, the main programme often starts playing before the ads start playing. It seems that video.js connects to the CDN of the main content initially and then contrib-ads checks if it needs to play prerolls. A few seconds of the main content is sometimes played before this happens and only then does it start to play the adverts.When using videojs-contrib-ads to create an ad