In my opinion it's just too difficult to swap the valve type i.e. to support Schrader valve - it shouldn't be necessary to resort to YouTube to figure out how to do this!
Having said that, once swapped the pump does work well.
Thank you for providing feedback to us regarding the valve on this Track Pump. As indicated, you need to manually unscrew the valve head and reverse the spacers inside to switch between Schrader and Presta. The 5th image on the website product page indicates this but a video is easy to understand as well. So save time, some customers pick up a small brass Presta vale adapter negating the need to swap the pump's valve each time. If you fast forward to 1:10 in this film it demonstrates how to swap the valve's inner workings in a few simple steps: https://www.youtube.com/watch?v=Kp-8YP4C_pM
Peter Lazarus, National Cycling Manager, DECATHLON