I was watching The Amazing World Of Gravity (Full Physics Documentary) | Spark on Youtube, and I didn't quite understand a certain part. From 5:00 to 9:00, Professor Jim Al-Khalili was recreating Galileo's inclined plane experiment. At 7:07 in the video, the data didn't seem to make sense. I think he had an error for Cup #1.
Yes the figures are off, but they are not using a very accurate measuring system. One person says stop and the other person moves the glass. Between cups one and two should be the least change, as the difference was the last quarter of travel, where the ball was moving fastest. They have the greatest change there, so he may have gotten a digit wrong in cup one or two.