after using video.js "s dispose () method, the < video > tag is removed, and
I use

var div = document.createElement("video");
div.id = "mydiv";
div.style.font = "bold 14px" ;
div.color = "green";
div.innerHTML = "Javascript DIV";
document.body.appendChild(div);

create a video tag and then use videojs ("mydiv") to initialize this video tag. Why?