I found this gif animation in Twitter as shown below. Now I want to know how that is done. I wish to put flickering effect on any still image. I'd like to use that technique on not just still images, also image sequences. Thanks in advance.
Idea: Distortion of image/movie coordinates in the material.
Step-4: Now, compute the 2D Noise based on the vertices of the plane then use that noise as UV coordinates in the UV Map Data Output node and adjust the parameters of 2D Noise group-node based upon your requirement,
A similar range of effects can be created with shader nodes alone - (plenty of knobs to fiddle with to adjust it):
The 'Mix RGB' node is being (ab)used as a convenience, to mix XYZ vectors.
The 'Location' fields in the Mapping node are keyed.
Not quite the same depth as your reference, but I'm sure it can be tweaked.. or if you don't mind being uneconomical, you could even play with real refraction.
.. and the .gif is a bit crunched.