I watched it when it aired at 3am, because the novelty of seeing DT on Canadian basic cable was too good to pass up.
Overall the episode was okay. The guy putting the series together didn't seem to be all that into progressive, but he showed a decent level of interest, and gave it a fair shake.
There are a few things I would have changed, though this is coming from a very different perspective than his, so I'm not faulting his approach; rather, just adding my own take.
For DT's segment, I would have given specific mention to a song or two, or an album or two. Still, they came across quite well in the time they were given. The special also made it seem like DT was mainly a force in the genre in the early 90s. They were, but I'd say within the progressive scene, DT are still a pretty significant band.
I would have cut most if not all of the stuff dealing with Dillinger Escape Plan. Based entirely on what I saw in the episode, they don't seem significant to progressive music, or worth covering. I would have put something like Opeth in that segment (I mean, their name was literally next to DEP on the chart the show had drawn up). They're just much better, and I think they would have provided a better example of that element of prog.
I also would have included at least a passing mention of Porcupine Tree. Their style is a side of prog that wasn't even represented in the episode.
I know he was a fan of theirs, but Mastodon, IMO, received a bit too much coverage.
I did like how much focus was given to Rush. If any band deserves that kind of recognition, it's Rush.
Overall, it was a decent episode. I would have done certain things differently, but then music is one of the most varied and divisive things there is, so that more or less goes without saying.