fix sumTimeplayed

public/react/src/modules/courses/Video/video-play/index.jsx

@@ -123,6 +123,7 @@ export default ({ src, videoId, logWatchHistory, courseId = null }) => {
         isLoging = false
         isSeeking = false
         pos = []  //有效时长重新累计，算新的一遍
+        this.sumTimePlayed = 0
       }, true)
     }