It takes about 5 seconds to read an average length comment.
Lets just assume perfect efficiency and then handicap it to account for lunch, peeing, pooping, killer bee attacks, etc. How about peak efficiency * 3/8, which basically says you only expect your workers to 'work' 40 hours per week, but in an 8 hour day only actually get 3 hours of work done?
Lets say a long youtube comment takes about a minute to read at most, and since we aren't going to quiz people for comprehension later we just need them to see if there is anything objectionable in the comment, we can take 1 minute to be a hard upper bound for the time it takes to handle one comment. The shortest comments take around 5 seconds. Let's assume the average is about 15 seconds (most comments are less than 1/4 the length of the longest comments).
So given the above they can do (3 hours/day * 60 minutes/hour) * 4 comments/minute == 720 comments/day. If we are forced to hire in the US we can easily find people to do this work for $25/hour working from home.
So every human review costs ((8*25)/720) == 27 cents. This is like 1/10th of your estimate and I feel like I'm going out of my way to make the numbers unrealistic in your favor.
Realistic numbers would be that it takes 15 seconds per comment on average and you hire people part time so they don't get burned out on reading comments (or full time but only part of their day is spent reviewing comments). With the same numbers as above, but not paying them to poop and pee for 5 hours out of an 8 hour day gets the cost per review to like 8 cents.
Lets just assume perfect efficiency and then handicap it to account for lunch, peeing, pooping, killer bee attacks, etc. How about peak efficiency * 3/8, which basically says you only expect your workers to 'work' 40 hours per week, but in an 8 hour day only actually get 3 hours of work done?
Lets say a long youtube comment takes about a minute to read at most, and since we aren't going to quiz people for comprehension later we just need them to see if there is anything objectionable in the comment, we can take 1 minute to be a hard upper bound for the time it takes to handle one comment. The shortest comments take around 5 seconds. Let's assume the average is about 15 seconds (most comments are less than 1/4 the length of the longest comments).
So given the above they can do (3 hours/day * 60 minutes/hour) * 4 comments/minute == 720 comments/day. If we are forced to hire in the US we can easily find people to do this work for $25/hour working from home.
So every human review costs ((8*25)/720) == 27 cents. This is like 1/10th of your estimate and I feel like I'm going out of my way to make the numbers unrealistic in your favor.
Realistic numbers would be that it takes 15 seconds per comment on average and you hire people part time so they don't get burned out on reading comments (or full time but only part of their day is spent reviewing comments). With the same numbers as above, but not paying them to poop and pee for 5 hours out of an 8 hour day gets the cost per review to like 8 cents.