I have literally read every stackoverflow thread regarding changing the video tag source dynamically via javascript in IE9, including the useful but not agreed upon posts he
Great news, I found a true solution to switching/changing videos in HTML5 video tags via JavaScript without using the annoying hack I tried to explain! It's unbelievably simple and it just took a LOT of experimenting with IE. Below is the code in its simplest form to work in IE:
And there you have it. Unbelievably simple -- tested and working in IE8, and IE9... If you are having any problems, please let me know.