The HD video player works well, but it lacks the ability to offer a playlist of related videos. Adding playlist controls to the video player would save the trouble of having to use third party apps that often limit the size of your uploads. This would not have to be overly complicated - a list of selectable videos next to the player would work well. Something that looks like this.
My business relies on the ability of my website to have many different videos that are only available to my customers. In addition to its ease of use, the ability to embed HD videos that are not hosted on YouTube or Vimeo (and are therefore much more difficult for users to illegally download and share) is a big reason that I use Weebly. Adding playlist controls would greatly enhance the HD player, in my opinion.