Can deep neural networks achieve real-time video analysis?
Nvidia seems to have published some white papers comparing DNN inference performance between high-powered CPUs and (of course) Nvidia GPUs.  (one example)

Ballpark seems to be that some systems can meet or exceed typical video frame rate thru-put for some class of DNN classification tasks.  Whether those image sizes and/or DNN architectures and hyperparameters meets your needs is one question, and whether desktop/server-class GPUs fit your desired power envelope is another question.