Hellfire Commentaries is a non-profit commentary group, that specializes in standard game playthroughs (i.e. not speed-runs, 100% runs, etc).
In addition to NTom64 (who handles most of the editing process of the commentaries, and is the main commentator), each playthrough has one additional commentator.
Fastest Thing Alive
There are also three other channels that belong to Hellfire Commentaries.
HellfirePlaythroughs - Features the playthroughs from the HellfireComms channnel (as well as playthroughs exclusive to the channel) without commentary.
HellfireFLComms - Features Hellfire Commentaries' movie commentaries. It is currently taken down because of copywrite claims.
HellfireMisc - Featurs Miscellaneous Content such as VG Music Picks, Online Mario Kart Races and Dramatic Readings
Ntom64 to HellfireComms
When Sonic Unleashed was leaked onto the internet, Ntom64 added one of the trailers onto his channel. Sega of America wrote a copywrite claim and suspended Ntom64's account. He then promptly made Hellfirecomms.