I ran into this problem a couple of times: Seeking through videos within the video.js player is possible in any browser except chrome. That means, clicking on the progress bar won't change the current position of the video.
In my case, the problem was the server delivering the video with the HTTP status Code OK (200). Instead, it should return Partial Content (206).
To check whether the server is the problem, embed the test video as in the online example on videojs.com, i.e. load the Disney video from http://video-js.zencoder.com/oceans-clip.mp4 instead of your own server.