There are many factors that can cause the videos to load faulty or freeze. The most important step to take is to be sure your browser and your operating system are up to date. Older computers and other mobile systems can have a hard time keeping up.
The next step is to be sure you have a strong and fast Internet connection.
After the above two things are taken care of, clear your browser cache. It's easy for browsers to get jammed, especially if you have been watching several different lessons in one sitting : )
If you have done all the above and still have troubles, please feel free to open a support ticket and we will help you dig deeper into the problem, you never know, it could be something on our end and we never know until somebody speaks up sometimes : ) Browsers, TV's, Websites, Cell Phones, Computers, ISP's, etc. all update and change rapidly.,..... keeping all these devices running smoothly together 100% of the time is impossible due to all the variables between devices but we do our best.