No doubt there will be ninety people along now to tell us what he did wrong. Then there will be an argument amongst them as to who knows best. Then the thread will sink gradually off the bottom of the page.
I think the pilot did a great job. He concentrated on the only thing that matters in this situation flying the airplane, he then took the safest option, a controlled touchdown in a field straight ahead The only way he could have improved on his performance would have been to perform a quick cause check to see if he could restore engine power. However given the low altitude and work load a decision to Just concentrate on flying the aircraft can't be faulted.
Unfortunately it is extremely unlikely that any of the forced landing training he got in his PPL helped him prepare for this kind of partial failure situation. Instead his training was probably all about the least likely scenario, a total sudden engine failure with no warning.
A partial engine failure, like the one this pilot experienced, is more likely than a full failure and in some ways more difficult to deal with as you will have more choices to make.
I tell my students the first thing is to go to level flight attitude and see if the aircraft will maintain Vy airspeed. If it will consider a flight path that will return you to the airport while maintaining a landable option if further engine power is lost. If unable to maintain level flight with the remaining power I tell students to close the throttle and plan a touchdown on the nearest landable surface, reapplying power as required to help the manoever.
With respect to the comment about breathing, all the training in the world won't prepare you for the stress of a real no s*hit emergency....
Finally in the best PPRuNe spirit of pedantry above all, I wish to point out that his checklist is wrong. The flashing beacon should be turned on prior to engine start not prior to entering the runway
Very well executed, as above, his PFL training may not have specifically covered this, but you can never cover every single eventuality, he did well under the pressure and made the right decision to land in what was available ahead.
Perhaps if he'd tried to turn back or complete a circuit it would've been a very different outcome, but he managed a controlled and survivable landing which is all anyone can ask.
The other points, though, that GPS really is obscuring the panel, and how many other people fly round with checklists dangling from the window like that? I couldn't imagine a more awkward or annoying way to store a checklist.
In the interests of learning from it - carb ice might be a likely cause of the rough running? He says 'carb heat checked' at the beginning of the video but it all seemed pretty rushed. Then there was a delay between the check and starting the takeoff run, with the engine at low RPM, which might have allowed ice to form.
As a low hours pilot myself I am paranoid about carb icing, and tend to do a quick recheck of carb heat just before lining up on the runway. On more than one occasion this summer the recheck revealed that ice had formed after my initial power check.
Looks like a hot summer's day judging by what he is wearing. I wonder what the humidity was.