Written instructions for exercises

It's good thing that there are video instructions on exercises, but the quality of the videos varies. On some videos there are detailed voice over instructions, but on some videos there is no sound or any instructions whatsoever. 

It would be helpful if there would be the key points in every exercise listed with bullet points, and perhaps the most common errors to avoid, also. If you are just looking at the videos with no instructions, you might miss some important points and even excecuting the exercise in dangerous way. 

Also, watching the video instructions takes time since some videos are about one minute in length. It would be faster to refresh your memory by just glancing thru the written instructions. This is even more important if you are swapping an exercise in the midst of a workout and you have to search thru the list of exercises.