How to dynamically add texture to an object in a video and get a new video? I have a video in which there appears a wall at some point. Having that video as input and a photo (that could be new in each interation), I want to get a new video in which the texture of that wall would be changed with the photo. 

I mean, my program must get as input the same base video every time, and a new photo.  It should generate the new video with my photo as the wall texture. Of course, I could prepare/mangle the video before the process, get whatever info I need to do that texture change dynamically, etc.

My questions is, what technique/software do you recommend to accomplish this? I'm a newbie in the field and want some direction/light from some experts so I can then dig deeper.
If I understand you correctly, this is traditionally done by compositing programs such as Adobe After Effects.  You could track the wall and then replace the wall with an image but it's going to be a lot trickier if anything is moving in front of the wall.  (You would need to make a rotoscope mask to tell it where not to render the image.)  You could then simply change out the image that is being applied to the wall.