I tried it with Microsoft Edge and with Google Chrome. (Internet Explorer no longer appears on my computer).
The first time through with Microsoft Edge, it worked. All subsequent attempts failed.
Logout and login again... didn't matter. Tried it on BBG and BGU 2.0. Also on ABGU. Failed on everything I tried.
Resetting a new end point always caused the video to restart at the begin loop point, but it played through the end point every time (after the very first loop I set).
Google Chrome never failed.