I will agree that iridium plugs do last longer. There is a side note here that no one has addressed. Today's gasoline has many additives to ensure a clean fuel system. Most people add products like Seafoam to assist in keeping the system clean. These additives adhear to the spark plug, they never totally burn off. The electriod on a standard plug does errode quicker than iridium, but as it errodes the film that additives leave also burn off. I've worked on lawn mower engines up to full race motors. This happens to all motors. Put fresh plugs in with the cheapest gas you can find without many additives. Run engine for a short time and pull plugs. If engine is properly tuned the plugs will have look almost new under a magnifying glass. Now do the same thing with top tier fuel or just put some seafoam in. The plugs will have a minute amount of glaze on them. I run standard plugs on all my carbed vehicle and change once a year, it's cheap to do. Now the newer injected vehicles do have a hotter spark and will burn standard plug quickly. I also doubt that the video is 100% correct. How old were the old plugs. What was the gap on the old plugs. What was the engine temp on the two runs, same? What was the ambient temperature? What was the humidity? What correction program was being run on the dyno? I can take the same vehicle on the same day without any changes and get a 3 to 5% various. So, what does all this mean, run regular plugs if you like checking the condition of you engine, spend a few bucks and put new ones in. Or put iridium in and forget for a while. I know a lot of you wrench on race vehicles, what is your take?
I don't look at the Iridium plugs as a performance item for HP but rather a item that will be easier on the ignition system, as a standard plug wears it can require as much as 40% more power from the coil to produce the needed spark, the coil will provide that power but it is harder on the coil long term when it has to do that.
With the Iridium plugs they don't require as much power from the coil to produce the same amount of spark so the coil is not stressed long term.
Other noted benefits of the Iridium plugs are quicker starting due to better spark, improved idle, better power delivery and possible better fuel economy.
I know that both my Victory and Harley Davidson benefited from switching to the Iridium spark plugs over the OEM standard plugs. Both bikes did start quicker, both bikes did idle better, now the power is not enough for you to feel and fuel economy is a subjective item depending on how the riders uses that right grip.
I think the thing that needs to be looked at before changing from the standard plug to the Iridium plug is to make sure there is a direct cross reference for the plugs. In the case of the Victory, Harley Davidson and this Yamaha all three have a direct cross reference for a replacement Iridium plug.