He doesn't specifically talk about underground steroids. He also speaks about pharmaceutical procedures, aseptic processing and compares it to a UGL he was invited to in holland. He also shows photos of the lab setup. This is all from memory but it's a good watch. Talks right back to the 70's near the start, tells how gear used to be predominantly pharma grade and that was the standard so gear was safer, then talks about the emergence of china and the difference between chemical processing plants in china (where 99% of UGL comes from) and pharma processing plants. He looks at a study done by the Harvard courant in 05 (I think) which ordered popular UGL labels from online and then tested them, shows the results. He also then talks about the testing he did (similar setup, ordered UGL from online) for his anabolics book in 07 then in 2010 and shows his results. Basically, he shows that there are chemicals like furfol (used in the construction industry), various forms of plastic, estrogen, corticosteroids and a bunch of other harmful and useless stuff. Obviously this is mainly contamination of the powder at a processing level however some (mainly the plastics) are a result of contaminated brewing. For example, storing the powders in the wrong type of plastic container can cause it to contaminate the powder, stuff like that.
I have a lot of respect for Llewelyn, he's got a lot of knowledge and has quiet a few good vids.