I just looked at the latest Ultrax kill. His UA uptime is pretty low, only 89%. And his Haunt uptime is even lower. Haunt should be cast on CD, and have the 96% uptime or greater like he did with corruption. Corruption also fell off and had to be recasted because he didn't Haunt on CD.
He used his 4pc only once....Soulburn should be used on CD with the 4pc. His opening is also off. The general opener for afflic is pre-pot >pre-cast Shadow Bolt > combat > CoE (if needed) > Activate Soulburn > Haunt > DS:Felhunter > UA > BoD > Corruption > Shadowbolt (for the third Shadow's Embrace stack) > Use the activated soulburn for soulfire > Shadowbolt filler. He used DS:Felhunter after dotting, which does absolutely nothing. Demon soul gives us a buff, so dots only know if we the buff when they're casted or refreshed. So his first set of dots weren't buffed, first BoD was never buffed, and only got like maybe one or two dots worth of that buff for the first use. In other words, pop before dotting.
He's probably overclipping BoD. BoD is only clipped when Buffs present > Previous buffs when cast. Simply put, if you put BoD up with DS, don't clip it when you don't have DS. Never clip your first BoD since it is amazin (lots of procs and DS:Felhunter).When in doubt, don't clip.
He also did not shadowflame once. For all specs, you shadowflame on CD when in melee range. This is especially important for demo/afflic because that's an extra dot for our felhunter to chomp on. For affliction, once you hit the 25% execute phase, that's the only time you stop shadowflaming on CD. All you do at that point is Drain Soul, cast Haunt relatively on CD (relatively meaning as close to on CD, but only after Drain Soul ticks and not before one), and recast BoD if needed. Every other dot will auto refresh.