It was already common then, I gather—the ex-developer-product-owner guy who showed it to me (in the course of doing something else) didn’t seem to think it was remarkable, just an assumed capability. I don’t recall the name of the product, but it’d record all the input and page content for an entire session, you could watch it play back like a video. Exactly like standing over someone’s shoulder while they used their computer. Creepy as fuck, but some genius renamed “spyware” to “telemetry” and that was enough to get every developer on board because we’re super insecure and will jump at the chance to pretend we’re building Mars rovers or something else real while we make yet another “app” the world doesn’t need (I suppose that’s why that label was so successful at changing attitudes, anyway)
Click-mapping came earlier, and there may have been a few places mouse-movement and cross-page-load session tracking some sessions, but I don’t think it was a “just turn it on and leave it on” thing for even most large sites. And a lot of early heat maps came from user studies, which is the right way to do that.
[edit] also, that just happened to be the first time I’d seen a single session represented that way, rather than aggregates. Again, it wasn’t some brand-new thing then, it’d been around long enough to have multiple companies offering it as a service, not just an internal tool at a couple giants.
