obvious privacy concerns aside, who the hell actually needs this?
If something I do is important enough to remember later, I do save it (bookmark, screenshot, screencast, whatever). This doesn't need to be automated, esp. since it seems to require 25-50 GB of diskspace to do anyway.
For users, this is a solution seeking for a problem. For megacorpo this is just more data harvesting, even if it's "only local" for now. Hard pass, nopety-nope-nope, also arch btw and so forth.