These requirements and guidelines are intended for creators. Exceptions are possible, as long as the video is useful and high-quality.
Videos must have either a recording of a human talking, or a real human voice narrating via voice-over. While it's possible to fit a computer-generated voice organically into a video, in 99% of cases it's a sign of lazy low-quality video. Videos with no voice are allowed, but only if they are how-to videos, showing a particular use case of a product (how to mount a GoPro 9 on a motorcycle).
There must be a real human in the video, talking to the camera or interacting with the product. Some product reviews re-use the same video intro (usually recorded by somebody on Fiverr) for many different videos. That's not allowed. Human in the video must talk specifically about the product(s) reviewed.
When people watch a product review, they expect that you, the reviewer, have personally interacted with the product. Otherwise the video is not nearly as useful. If the video reviews or mentions multiple product, we don't expect you to have all of them, but at least one must be present in the frame. This does not apply to non-physical products (travel services) or very expensive products (a vehicle).
If you were paid for review, disclose it. If you received a product for free, disclose it. It is the ethical thing to do, and is required by law in many countries. Make sure to correctly set the type of your video. Available types are "Review", "Comparison Review", "Top 10", "How To", and "Other".
Aside from being unethical, taking content from somewhere on the Internet is, in most cases, illegal. Licensed/quoted content is ok, provided that said content is not the majority of the video. For example, you can quote the manufacturer's description or show parts of product promo videos, but you can't make a video where you just read aloud the manufacturer's description, or string together other videos that talk about the product.
QualiTube is a platform for product enthusiasts to share detailed insights about products. It's unlikely that the video is insightful and in-depth if it's under 5 minutes.
This really falls under the 'no plagiarism' point, but deserves a separate mention. Too many 'review videos' simply read customer reviews from marketplaces these days. Instead of reading other customer opinions, you need to share your own.
Making great reviews will make people more likely to support you, sub to you, and not click away. Everybody wins.
Play that piano, nerd out about the camera's photography settings, show the router's median latency on a chart instead of talking about it.
People use products differently, make sure to showcase as many features as possible.
Properly formatted text is more engaging to read and has a higher conversion rate.
Showing that you did reviews of similar products shows viewers that you are more familiar with the subject matter.