If you are talking about the 2 first movies the addon list is (or at least the visual part. I had 107 addons enabled last time i checked, which also explains the mess around the minimap

):
Skinner (makes the chatframe the faded black color)
Prat (my char addon. Colors char names etc. Couldnt live without it)
Eavesdrop (The small square to the right of the chatframe. Shows dmg done and recieved in an easy-to-read way)
Assesment (to the right of eavesdrop. Its a low memory dmg meter. Its similar to recount, just dont have all the pretty graphs etc. But on the other hand it uses 1/10th of the memory recount use
Scrolling combat text and the SCTD "addon" (The dmg on the middle of the screen. I think SCTD makes the dmg showing in a diffrent way... Cant remember though. Been using those 2 addons for like 1½ year)
Bartender3 (for all hotbars. It also makes the bars invisable. I got 5 bars on my screen that only apears when i mouse over them for buffs etc. You can see an example of the mouse over bars in the first vid just after first pull)
AG_unitframes (Used for all the unit frames)
Cooldown timers 2 (Shows cooldowns for all spells with a cooldown to the right on my screen. Usefull for pvp when you quickly need to know exactly how long till you can use frost nova again. Also makes the popups when a spell becomes ready)
Morganti's buffbars (The pretty buffbar to the left of the minimap)
Uhm. I think that was all. Lemme know if you got any questions