You made me curious so I did some back-of-the-envelope math. An average of 576K hours of video is uploaded to YouTube every day [1], which is 4.032M hours per week. If the reviewers watch all the video at 1x speed and work 40 hours per week, you'd need about 100K reviewers to do the job. (This is just to watch the video -- not including any additional work done to annotate the video with whatever information you want out of your reviewers.) If each one costs $30K a year (probably a lowball estimate including salary, insurance, etc.) it would cost a total of $3B per year. YouTube makes $4B in revenue per year and roughly zero profit AFAICT, so there's no way this is feasible.
[1] https://www.quora.com/How-many-videos-are-uploaded-on-YouTub...