I'll start this post by stating that I am in no way an expert in user interface design, I spend enough time on YouTube as a user to notice some glaring flaws. The fact that I am not an expert and yet still feel qualified should highlight on how bad YouTube's UI really is.

What's Wrong?

I'll start with seemingly the most basic part of the UI: viewing a user's uploads. You should try this with me now. Go open an uploader's uploads page. At the bottom middle of the screen there is a button which says "Load More". Click this button and watch any video on the part of the page that loads. When you have finished enjoying your video of choice, hit back. Oh look! You are at the top of the uploads page again. This problem is even worse when an uploader has hundreds and hundreds of videos. As a user, you must rely on an uploader organizing all of their videos into playlists, or rely on searching by video name (provided you know part of the name of the video you want to find). I have no idea how this has continued to pass even the most basic of user experience tests for years.

How to Fix it

There are a few options here. First, make each video open on a different tab or different window. This is a simple fix, but I personally think that any design that requires the user to manage multiple tabs is an example of poor design.

Another easy option is to move back to a standard page system. This is not as "sexy" of a design option as the single page model, but the user can actually pick up where they left off.

The final option could be to find a way to remember where the user left off on the endless scrolling page. I'm not entirely sure how this is implemented, but other sites utilize it. Go to Facebook, and open a link partway down the page then return. When you navigate back it remembers your position and returns roughly to where you left off.