I helped a company scope out a service like this out. I hated it so much that ever since, I simply turn away from anything that would require me to use them. Needless to say, the company I was testing it with did not continue to use the service.
If interviews tend to be a little awkward to begin with, I find these online tech screeners to be over the top awkward. And with the results, we had a hard time determining how much value they added, because it was clear that the results were sub-par.
What you mentioned isn't that different from interviewing with a human on the other side. All interview performance is kept on record at most companies. For 5/10/15 years or even more.
That's why it's not a good idea to interview at a place when you're unprepared. Not only are you wasting both your and the company's time, but you're also hurting your chances of getting an interview call from them in the future.
I have seen a lot of people I know make this mistake -- not preparing enough for a interview, failing badly, and then applying to the same company 6/12/24 months later, and not even getting another interview. Very frustrating.