There is a convo going on right now about the optical flow style stuff. A lot of it is centered around UE4 actually so it may be helpful.
Motion Vectors (for animated textures), How do you generate them?
We are primarily talking about the method shown a few years back by Guerilla Games that more recently Klemen Lozar wrote up for UE4: Klemen Lozar's Online Portfolio
Most studios seem to have adopted the concept if not the specific implementation, so I wouldn’t be surprised to hear Epic is making something more built in, but although parts of it are still hard to get a grasp on, the results are so valuable that most everyone is rolling their own anyway.