What he's talking about is that the CGI in B5 was filmed in 4:3 and not in 16:9 like the rest of the show. When they did the "high res" releases they had to make the choice of doing everything in 16:9 or in 4:3.

In 4:3 it looks good and like the original airing show, in 16:9 any non-digital/composite shot looks freaking fantastic. But once you get to any digital or composite shot it takes a nose dive in quality.