For the complex computing tasks the GPU provides real benefits.
Regarding Why? check the article and other materials on NVIDIA web site.
WHAT IS GPU ACCELERATED COMPUTING?
From personal experience, very rough numbers that are actual for today, for example, the specific version of deep learning facial recognition needs around 300ms on i7 to process one frame per core (in real life it will be something like 12fps total) and 35ms per frame on the old GeForce GTX 650 that has 384 CUDA Cores (~25fps). If to use something like TESLA GPU Accelerators for workstations then there will be 2400 - 2800 CUDA cores available.
My understanding is that it can be significant, but it's almost a moot point because a lot of VMSes don't offload to the GPU anyway. Genetec has been making some noise about doing GPU decoding, but it requires NVIDIA Maxwell chipsets, and you're looking at another $200 at least (some are over $1,000) for the video card, and it requires a bigger power supply, in some cases much bigger.
We haven't tested GPU performance. We had a discussion about this in 2014 in which only Avigilon was cited as supporting NVIDIA CUDA. It's been on the list to potentially test, but it doesn't seem like much significant has happened in GPU support, so it's pretty low priority.
Milestone's new 2016 client uses Intell's Quick Sync system which basicly uses the on-board Intell Graphics chip to enhance preformance. Claiming up to 75% reduction of CPU load.
All nice, but I rather had it that they made it work on Nvidia cards. It can be intresting if you're using the correct CPU's of Intell.
It would great but the software just is not there for it yet. Unfortunately other than security video applications there really isn't a market for it. There isn't anything else i can think of other tan maybe some multi-screen jumbo-trons that you could use it.
would be nice though, if i had to ballpark it I think a 2GB Nvidia card for about $150 could do about 64 720p cameras with no problem and leave the processor nice and cool. That assuming all the software was perfect though.