Does anyone know if you can upload product videos on Amazon without being brand

Stella, one of the brand registry features is the ability to upload product videos; Amazon states that sellers who have registered their brands can only upload videos. But, I have seen in one of my clients’ accounts that he is not brand registered, but we still have the option of uploading videos. So, I think in some rare cases, Amazon will give you permission to upload videos on Amazon without being a brand.

Yes. Without a brand registry, videos can still be added. More than ever, adding videos is simple.
In the past, only brand owners could upload videos. All vendors with a Pro account can now access it. You only need to follow the requirements for Amazon product videos.