That C21 is actually a C22. I doubt anyone will find anything useful in this video - far too fast and no realistic display of techniques, procedures and difficulties - particularly with the mudguards/fenders
The only fault is using a cordless electric pump for the tyres over a manual pump. You should have inflated partly just to re adjust the tyre seating in the rim....... something that you used to do in your older Sickbiker videos....so why the electric pump method? The innertube itself maybe faulty if it doesn't inflate evenly without being inside. You may/may not have checked this but we don't know in this video.