I don't think a good knife review needs to have testing. We can infer a lot from the construction, materials, and mfr. reputation.
I do agree that the review should not be done immediately after receiving it. Those videos should be titled 'first impressions.' I think the knife should have been used a bit, so that the ergonomic and mechanical faults, if any, could be discovered and exposed.
Sometimes, I have my choice narrowed down to about 3 models, and I just need one little tie-breaker to make the final decision for me. For instance, someone saying: "xx knife has so much traction on the grip that it tears up my pants pockets when I clip it on." That knife is immediately ruled out for me, as I've never had a problem with keeping my grip on any knife. Sometimes, there's a feature or lack of features I was unaware of, until someone pointed it out.
I guess what I'm saying here is that I think a good review points out most of the things (both good and bad) that are not immediately obvious from reading the knife's specs or just seeing photos or videos of it.