In some sort of attempt to un-derail (re-rail???) this thread, I do have an example of what using a low level CB Zither! in a high burst DPS environment looks like. Me and two friends, and a PUG (bet you can't guess who the PUG was!). My instructions to them were to try to steal all my kills.
Let analyze this video.
On wave 1 and 2 you play as typical over promoted player. You rush without rime or reason, leaving single and spreaded out targets around the place. Party stays behind and need to deal with it. Why Avvars stay behind? Still Duelist player greatly showed how powerful burst damage can be, wiping whole group at the end of wave 1 with single broadside, right after you attacked will cool beats on 3 targets and get around 2-3 ticks of damage.
On wave 3, when group at last get ahead of you, your cool beats were just useless, you ticked maybe twice. Still at the end of final group you just run ahead of group and deal some damage. Player who played Duelist do it right, but those avvars? Nope, they too slow, either lacking passive for speed or just ability to run. Avvar shoudn't deal with single targets, LW should kill it.
Wave 4, you got on first and run way ahead of group leaving for them those "ticking" targets. But all this rush at the end was wasted because few mobs spawned way behind spread widely group of players. Time wasted, probably because of your rush.
Wave 5, typical over promoted gameplay. 3 players staying close to each other and one running around soaking damage from everywhere, pew pewing with cool beats at random direction. Without billion cunning and tons of healh you shoudn't try it at home. Huge numbers of kills comes from this wave, still duelist got more kills. Avvars play poorly.
Sum up.
Maybe you told this group to "steal" your kills, but it's obvious that they don't know how to do it. Me as Avvar, would not run as last player (what was often in your video) but as first. I have 2 passives to boost my speed and even I could get your song too. I would leave single mobs and focus on groups ahead hitting them with crushing leap and start and maintaining LW all the time. On venatori it should work very well because general units, archers and zealots I can kill with Crushing Leap as it's own. 4k damage isn't that hard to get really.
Scoreboard, nothing new. We all know that the more targets you "tag" the better xp you get. Cool beats is great tool for it, not doubt. Still maybe giving barrier from time to time would be even more beneficial to xp? We don't know, it's impossible to test in that type of dynamical environment. XP in general does not directly applies to being effective, with AW being probably prime example.
What we can say about Cool Beats in general after those videos.
1) It works greatly with highly promoted players, which can just rush or move around casting it on everything.
2) It works with soloing where you have full control of spawns, where mobs move etc.
3) It has great synergy with Encore, still you need to get kill by either aoe or direct damage part, so in group setup when targets will be killed by other player it could not work that great.
4) Best spell Virtuoso has on faction bosses, strangely because it's cold it's in general best elemental type for it.
Flaws
1) Cool beats can't crit. This makes building virtuoso...strange. On one side you want crit damage to boost Power Chord, basic attack and Killer Set but on the other hand Cool Beats are based only on base damage and +attack%.
2) Targeting. I don't know how it works on console, because your videos shows godly aiming skills in terms of changing targets. On PC I have either mouse or TAB, mouse is for everything (including moving camera) and TAB sometimes makes stupid choices. Problem with TAB is that it maybe change targets in good way but makes bad "first" choice, so in most cases for close range I use this auto aim (or whatever this soft targeting is cold) and mouse targeting for longer range.
How it affect my gameplay? I can't just run ahead as virtuoso and tag everything on way, I will be dead. So I will stay with group and will use cool beats from range. Auto aim in general is more made for archers etc, so it sticks with target and even choose the closest one. This forces me to manually aim with mouse and tab which is slow and annoying and breaks effectiveness.