The radius of the fearful effect starts from the position where Toth lands after he leaps. So if your range dps were positioned such that they were within the effect radius of Toth's landing spot, they will end up getting fearful.
This is more or less true, but you have to realize fearful will happen right before toth leaps, but either way it is about positioning them right to make sure dps dont have to stop early.
For melee dps we usually have toth and zorn switch sides, while tanks stay in the same spot, and make the melee run in a U shape between the two tanking spots to avoid any and all aoes during the transition phase. As for the berserk aoe from toth, they should be poping a def CD, or jousting (run out and then back in) before it goes off (they should have about 2 or 3 seconds after the red text to get out).
As for people being close to toth getting the fearful, you want to make sure you have about 35 to 45M between the tank spots to avoid doubling up aoe's and to prevent both tanks getting fearful, once again a positioning thing.
On a side note there are multiple ways of doing this fight, and multiple ways of positioning them, so dont feel like you're stuck doing it one certain way cause of an video/guide.