Considering Alexander Arguelles is the populariser of shadowing and people use the method as described by him, I consider his method should be top-notch. He’s definitely very practiced in his own method, which he’s been using for years for many different languages.
As per his Russian level, at the time of recording, as far as I’m aware, his Russian was already high. I saw in old forum posts dated years before the recording of this video (at least a decade before), he had mentioned he had read lots of Russian literature. So in terms of reading ability, it was upper advanced. Back when Russian was his focus, I think he may have also mentioned that he had also spent one month in Russia doing an intensive learning session with a private tutor. I’m also not sure how much he had been upkeeping his Russian since then (in the recording he was up to lesson 70 aka day 70 at the very least), but considering these factors, I honestly expected a better pronunciation, if the method is meant to give you good pronunciation.
Also, I am learner of Russian, not a native speaker. I have ~450h of listening to Russian, which 90% is probably reading while listening. To me, he has a very obvious English accent for individual words. Not to mention his intonation at a sentence level and hesitations. He is understandable, but from the first word, you can tell he’s a foreign speaker who has not focused on pronunciation. From watching other videos with him, I think he does not consider pronunciation a priority, pretty much ever. I’m just saying that it seems that the ‘father’ of shadowing does not have good pronunciation, despite from using shadowing. He’s understandable and I guess that’s his goal.