A couple things first-
Tell us about the truck, year, any work thats been done, modifications, other problems, etc...
I will not reseal a nipple on a high pressure rail, or the top of an injector. I've seen far too many failures and HP oil leaks.
If it is 04.5-07 has it had the updated stand pipes and dummy plugs installed.
What was the reason for the injector o-rings and the nipple re seal?
Based on what was stated in the video I would think this is a HP oil leak. But you'll just have to test and let us know the results.
Electronic testing-
Codes?
FICM Voltage?
ICP Voltage KOEO?
ICP Pressure idling and when it occurs?
IPR percentage same as above?
Power balance(Cylinder contribution test)?-For this test you'll need something more in depth than a handheld(IDS, AE, etc..)
Physical testing-
Air leak test?
Bubble test?
Balloon test?
Did you replace the copper washers on the injectors? If not, then don't start that truck again, you have work to do. If so, do you have all 8 of the old ones?
If you have the ability to do the computer testing, then do it and let us know the results.
On the physical side, the first one I would do is the bubble test. Its fast and its simple.
Remove the secondary fuel filter and leave the cap off and the filter out. Cycle the key to fill the fuel filter housing. Remove the key from the ignition. Use the starter bypass wire on the passenger fender to crank the starter for 30 seconds, longer if you're willing to risk overheating the starter. Watch for air bubbles rising in the fuel filter housing. If you have air bubbles, then you have a leak on your o-rings. Other things can cause this, but that's the most common reason.
If you do not get bubbles, repeat the test. Then once the starter has cooled, repeat again. Sometimes it takes several times.
If you ever get bubbles, it is a fail. There should be zero air bubbles to pass.
If it fails, you can unhook the feed line to one head and cap it off. Then retest. Then repeat with the other head. This will tell you if the leak is on the drivers side, the passenger side, or both.
Balloon test follows the bubble test. Unhook the fuel lines between the fuel filter housing and heads. Put a balloon over each line. Crank the engine in the same manner as the bubble test. If the balloon pulses. The most common issue is that you have cylinder pressure making it past the copper washer and the bottom o-ring on an injector on the corresponding bank.The other possibilities are a cracked injector or head.
If there is a fail then proceed as follows. You can isolate the cylinders by removing all 3 glow plugs on the offending bank and repeating test. Note if any pulses are present and move the glow plug to the next cylinder and repeat. Do all 4 cylinders on that bank.
Next would be an air leak test.
I remove the IPR and have a fitting I can connect in order to pressurize the entire HP oil system. If you do not have the necessary fitting, then you can order online or you can hook into the HP rails under the valve covers with commonly available fittings.
If you have the IPR fitting then you do not have to remove the valve covers until you have heard a leak on one side or the other. Remove the CCV on the drivers side and the oil fill on the passenger side. Hook up shop air to the IPR adapter and listen for your leak. Once the leak area is identified, you can go through the effort of removing that valvecover.
If you do not have the IPR adapter, then you are needing to get under both valvecovers anyway. Though if you have an 04.5-07 engine, you could test the passenger side by hooking into the ICP sensor port.
Again, any leak is a fail.
While not recommended, I have done this one in a walmart parking lot to help an old man out.
If you have no way to air test it, your next option is to remove the valve covers and start the truck. Try to observe as much as you can and see if you can spot a leak.
This test may not allow you to spot your leak, but, if its bad enough it may show.
I see that you have an SCT. At a minimum you can get the FICM, ICP and IPR numbers. I do not know if it will show ICP voltage.