AVR is probably the most dummy-down addon I've ever used.
I thought deadly boss mods was one of those raid addons that really just made it much easier for the average raider by giving you warnings that tell you when to move. AVR takes it even further. The main aspect of AVR, for raiding, is that it puts a circle (usually red) on the ground showing you where to not stand in order to avoid damage.
For example - Rotface - when the big ooze explodes, AVR puts a red circle on the ground at every point at which an explosion will land. You will notice that there will be a ton of red circles overlapping each other at the area where the melee were standing.
Another example - Lich King hard mode - shadow traps are a pain in the butt when you are first learning the encounter. AVR puts a big red circle on the ground where a shadow trap is about to form. It really helps you to see exactly how far you have to move so that you can just stand right next to that red circle and know you won't get hit by the shadow trap.
It's also really nice for Malleable Goo on Putricide.
Another feature of AVR is that you can also draw pictures on your screen and send those pictures to everyone else in your raid that uses AVR.
For example - Blood Princes - you want all your melee to spread out when Prince Valanar casts his explosion (sorry I can't remember the name of it). Well, most guilds have the melee use the stage as the area they can use to spread out, but sometimes it's a real pain knowing who is going where. With AVR, you can draw little circles on the stage, signifying which spots melee can move to, and then assigning those spots to different melee raid members.
In that situation, it's like using purple or white flares, except you don't have to worry about aggroing the boss while putting them there.
Another example of that feature is in Sindragosa's room. You can draw out an area where you want all the ranged to stack up for phase 2. You can draw out the areas where you want ice tombs to be. You can draw a huge penis if you want, but after a while your raid members will get really tired of it.
*Note* This isn't a hunter-specific addon, but I've found it extremely useful as a raider so I thought I'd share it with the EJ hunter community.
If I'm not mistaken, it's a 2-part addon where you need both in order for it to work.
AVR - Addons - Curse
AVR Encounters - Addons - Curse