I did those all a long time ago. However, again that list isn't accurate because my 5km PR (not that it really matters or is much faster) is actually 14:29.....on an indoor track! But it shows people need to be more careful with fact checking and believing what they first see on the Internet as being truth.
Again, if you go by IAAF course standards 2:18:24 is my marathon PR on a "certified course". I ran 2:16:52 on a course much like CIM/Grandmas/Boston. If you're not going to count my 2:16, then nobody who ran CIM/Grandmas/Boston can count their PR time on all those courses either then. I consider my best marathon performance actually to be my 16th place at Boston because it was headwind day and I ran solo much of the race for a 2:19:12...which was probably the best paced marathon of my life...and it was only like 7 weeks after getting 8th at the USATF Marathon Champs in LA.
But this thread isn't about me. Anyway: I highly doubt Seth averages 4-5 hours a sleep each night for extended periods of time while training and filming that much. I think people can tend to exaggerate things on Youtube for clickbait effect a bit (I know I have!). I'm sure he probably doesn't sleep as much as me though because he has 5 kids....
Do I think he can run a 2:17 eventually and get an OTQ? Yes. But probably only because of super shoes/carbon fiber. I've seen all types of guys go from 2:21:xx to 2:17 in the new shoes. Back in my prime road marathon boomer days we ran in straight up EVA flats!
I will say it appears his understanding of some very basic principles of exercise physiology seems to be lacking...and that can be bad advice when being a "coach" or doing some sort of "training talk". I also believe he has quite a few illegal drone shots in some of his vids (But that is another can of worms all together). In any case I've also made the same mistake of trying to mix OTQ level road marathon running and MUT Running within the same season and failed misereably....for both '16 and '20. It is hard! Part of it is the personal bias of coaching yourself...which can be hard. In my defense though I was actually racing and training for things like 50-mile-100km+ mountain ultramarathon races and then trying to "drop down" to a road marathon too quickly. The fact that Seth actually doesn't really race ultramarathon distances (and he actually hasn't raced a ton of trail races outside of Pikes in general either) probably works in his favor for a faster road marathon (i.e. it's easier to stick with the same 26.2 mile distance between trails and roads).