I think that the best thing that Gravis does is make the uninteresting interesting. He could make a video about just about anything, and I would probably watch it. For example, he's able to talk about printers for 1 hour and 40 minutes, and he's able to keep it interesting that entire time.

A lot of his videos are also about things that nobody else is likely to ever talk about on YouTube. For example, he made a video about
CD-ROM Jukeboxes, which let a user put dozens (or in some cases, hundreds) of discs in a single enclosure.