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Often the reason different QoS documentation conflicts has much to do when it was published, as QoS recommendations are often evolving.
The reason why RT video has often been recommended not to be placed into LLQ assumes the latter has other "more critical" RT traffic such as VoIP. As video tends to be both more bandwidth hungry and bandwidth bursty, having it in the same queue as VoIP might degrade VoIP.
BTW, a "compromise" approach, if the RT video has separate traffic flows for its voice vs. its video components, the former can be placed into LLQ with other VoIP and the latter in a "great" service video class.
When it comes to TelePresense, as Cisco markets it like "being there", and it's often marketed to upper management, recommending it being placed into LLQ helps insure it gets the very best service. (Technically, TelePresense is really just HD video conferencing, but again, its "users" often are higher on the totem pole than those who use SD video conferencing. Often notice "QoS" differences between calling a sales line [often no waiting] vs. calling a support line? Sometimes QoS isn't about a technical difference but what's considered important to the business.)
Could TelePresense be adverse to other LLQ traffic? It can, but when you're doing TelePresense deployments, considering often who the "users" will be, you insure there's ample bandwidth for it (which would also help insure there's ample bandwidth for any concurrent traffic like VoIP, otherwise the latter might be adverse to TelePresense too.)
