Digital showers are fantastic and generally a lot faster to fit than rigging up a pump so labour will be cheaper , a grand ish must be for the newer types / styles of shower , you can still buy the older types .
Even though they are marked flow / return its worth ringing the manufacturer to ask if its absolutely essential.
I have just done it and the manufacturer said it didn't matter
I can only see one vid for some reason , as you look at the picture you have just sent , the seal is to the right on the elbow , not on thin round one on the left