I recently installed 3 similar Velux blinds. Unfortunately an error in one of the instructional diagrams caused me a lot of grief. The electrical contacts cover that requires removal from the top of the Left Hand Side frame is incorrectly shown (ringed in red) in the diagram as being located on the RHS. It took me a long time unsuccessfully attempting to remove it (without damaging the frame0 before it dawned that the cover to be removed was located on the LHS of the frame. My fault I guess? for following the instruction diagram. However while balanced at the top of a ladder with the sun blinding me- the two covers looked the same. Once you know how the blinds are actually very easy to fit. Shame that for a first timer they are let down by an error in the international installation diagrams.
Good video overall but a step has been missed...and i had to ring the velux support team today...For the benefit of others the missed step is connecting the electric cable to power the blind as per diagram 8 on the instructions. This step requires undoing the electric chain, opening the window manually, pop your head out of window and turn 180 degrees facing the top of the window, on left side of the window a lose cable needs to be pushed into the socket of the window. This cable is left lose by velux for when you install a velux blind.