It is a difficult problem to analyze from the video but you definitely seem to have a fuel
leak on the high pressure side. As others have posted, carefully tighten the injector mounting bolts to compress the copper washer. I always install new ones when servicing the injectors. That engine
should start fairly easily on three cylinders providing that there is good compression so I suspect there may be more than one problem. When was the last time that the valves were adjusted (should be every 500 hours)? Is the fuel
shut-off cable fully seated on the injection pump? If it isn't, the engine will never start. The injectors should be serviced (replaced or rebuilt) every 1500 - 1800 hours.
4-108s and for that matter all older 4 series Perkins
are generally indestructible if kept in a reasonably good service
condition which is why they have such a solid reputation. As with all diesels, clean fuel and clean air and a good starting source will make for a a happy and reliable engine.