Read it in the 90's. I remember one specific part where the inventor of the peeking mechanic has his Eureka moment, and has the presence of mind to give a thumbs-up/wave to the future, when they look back on his Eureka moment. I also remember that they had computer screens that were like plastic cloth that they would just unfold on whatever surface was handy. Sorry I don't have much more to go on. Please and thank you!
Pretty sure this sounds like Stephen Baxter's Light of Other Days even though it was published in 2000.
The key scene that seems to match is when one of the protagonists of the story, Hiram Patterson owner/CEO of the company that develops the WormCam technology.
In it, at the moment he and the team realize what they have (i.e. the Eureka moment) he looks up and states:
But Hiram, his troubles dismissed, grasped the implications immediately. He glared into the air. "I wonder how many of them are watching us right now?" Mavens said, "Who?" "In the future. Don’t you see? If he’s right this is a turning point in history, this moment, right here and right now, the invention of this, this past viewer. Probably the air around us is fizzing with WormCam viewpoints, sent back by future historians. Biographers. Hagiographers." He lifted up his head and bared his teeth. "Are you watching me? Are you? Do you remember my name? I’m Hiram Patterson! Hah! See what I did, you arseholes!" • And in the corridors of the future, innumerable watchers met his challenging gaze.
Though written in 2000, this novel was based on a short story of the same name from 1966 which was incorporated into a collection in 1972. This may be why you remember it from the 90s, particulalry if you happned to read it again as the later version.