Chuck vs Seagal
It would have been good to see more of the blackbelt testing in the Path beyond Thought video you mentioned. I would have also enjoyed seeing some of the punching and kicking techniques that one of the Aikidoka mentioned (Renosa perhaps?) which was supposed to be allowed in the blackbelt testing. It is interesting to note that the students being tested for promotion struggled with great difficulty once the fighting distance was narrowed. Whether they were still standing or taken down, the fight was basically over. It is good that Seagal was encouraging them to keep the "fight" going as it instills in them the ability to perservere against overwhelming odds.
With regards to Segals current physical condition, I don't know of any athlete who is excessively overweight by his previous standards and performs well in a sporting event ex: Olympic athletes, boxers, soccer players, Judoka, etc...
I certainly do not think it interferes with the more esoteric/meditative aspects of martial arts but it is not the ideal condition for combat. I see a radical change in Seagal's physique vis a vis his Above the Law film and in the Path Beyond Thought video. Although older, I do not see that radical physical change in other martial artists such as full contact fighter Joe Lewis, judoka Hayward Nishioka, Chuck Norris, Don Wilson, etc... I think it is a matter of dedication involved. In our discussion of the hypothetical fight between Norris and Seagal, if all else were equal, the result of the fight would rest on whoever was in better shape.
I have seen several interviews with both Seagal and Norris, as well as seeing them in person in recent years, and have found them to be especially cordial and considerate when discussing other martial artists and assessing their abilities whenever the question arrises. This is quite contrary when reading some of the negative comments attributed to them, especially Seagal, in the print press. Norris has seldom been attacked, maybe due to his PR, but unfortunately Segal has been much maligned.