You should always cut on the waste side, put your straight edge on the side of material you need. This is so if you accidentally cut a little off line, it's the side you are cutting off and don't need. You can always go back and cut the straight line again
I liked your video and the cat helping was a nice surprise. Being in the US I mentally auto-translated 40 mil into 0.040" which seemed like a pretty small adjustment.
Thank you for all these clear instructions! I bought a roll-up blind and was wondering if I could change to a roll-up device like the one you use in the video. Do you believe this is possible? (I think so, because I saw some on Amazon) Last question: How do I remove the end caps from each side of the pole on my automatic roller blind?
To allow for the width of the fixings. It won't always be 40mm, but you will always need to cut that bit extra material (based on the width of the fixings of your own blind).
Just a suggestion to get your videos looking a bit more professional - turn the freakin' TV off..! :) It is very distracting. And I'd echo what somebody said below - always cut on the waste side of the line. I saw another video on this same task - and the guy did it on the entire roller blind setup, all tightly rolled up - on the chop saw! Great result, and very quick.
Yes, turn off that stupid TV, get the cat out. Demonstrate how to cut the rod. The rod and measurements are the critical factors which you missed. Why 40ml for the fixings? Are they all the same? How to find out? Then cut your video to the basics needed. Thanks anyway, nice effort and somewhat helpful.