Efficiency of this constantly running time processor for an HTML5 video control bar
If you're worried about performance, this should raise a red flag:

someJQueryObject = $("#some-id");
...
someJQueryObject.html(aPlainOldString);


.html(foo) is almost certainly slower than .innerHTML = foo, because .html() does a bunch of extra stuff, like checking if it can use innerHTML, trying to use innerHTML, catching errors if that fails and using a fallback, etc. Also, using innerHTML is probably slower than simply creating a Text node and updating its data property.

I'd suggest replacing timeProgress = $("#time-progress") with something like this:

var timeProgress = document.createTextNode('');

document.getElementById('time-progress').appendChild(timeProgress);


And replacing timeProgress.html(progressHMS); with this:

timeProgress.data = progressHMS;


This will be a significant performance improvement and will also eliminate the jQuery dependency. Using a large GP library like jQuery to select two elements and update their text content seems like overkill anyway.

Here's a jsPerf demonstrating the performance difference.