Yes, the videos were at two different times. We do not know how much time between videos. Yes, they are both from the Brownsville Revival.
I'm sorry to hear about your back/hip problems. I will pray for the Lord to give you wisdom. You may want to try your idea to see if it helps. You can always discontinue doing it if it is not helping.
Here is a short video that is 1 minute 29 seconds long. It shows the proper way to sit and work on a computer.