Is this right? (Cat D4 7U with Bosch magneto with video)

the things that can give you problems are the kill switch as its a grounding switch and is normally closed in the off position. if it or the insulation on the wires is bad it will stop the spark.
bad plug wires will stop the spark these need to be the proper wire plug leads with metal ends not the silicone suppression as used today.

the spark plugs and there mating faces need to spotless so does the mating faces between the mag body and the engine. any dirt/grease etc can interfere with a good spark. magnetos rely on the return path between the mag spark plug and the block to work. even modern cars still rely on that path its just a bit more complex
a poor condenser will also affect the spark. often fit new condenser and points and a mag will work again and work just fine.the generic bosch condensers work just fine.

if it has good spark at the plugs but wont fire fit new plugs if it still wont fire try swapping the leads. i learned that with our d4 after fitting new leads it was opposite to what i thought.

the spark should be nice n fat n blue and thats not. yes i agree with OM change the condenser and see what happens.