How many people to review youtube videos?

There was a Buzz Out Loud episode in the not-to-distant past where the discussion of youtube came up. I can't remember the exact details, but the main point was that it would be impossible for google (the owners of youtube) to review all of the videos that were submitted.

And here is my calculation. How much would it cost google a year to do this? First, I need to pick some variables (and I will first do this symbolically - then you can put in your own values if it makes you happy).

• Submission Rate (s): This is how many minutes of video are submitted each minute (so the units would be minutes/minute). Just as an example, if only one person was using youtube and streamed their whole life - s would be 1 minute/minute.
• Pay Rate (p): How much do you pay a reviewer per hour (units: US Dollars/hour)
• Reviewer efficiency (e): How much of a reviewer's time is spent switching videos and stuff. This is a unitless quantity that must have a value over 1. For example, if a reviewer spent 10% of the time on stuff not related to reviewing, then e = 1.1. Also, this probably would depend a lot on the system that delivers videos to the reviewers.
• Number of Reviewers (n): I think this one is clear.
• Movie speed (v): I just thought of this one. What if the reviewers watch a video at a compressed rate. Movie speed of 1.5 means that a 1 minute video would only take 0.67 minutes.

Now for the calculation. No wait, how about a diagram?

The main point of this diagram is that whatever videos come in, have to be reviewed. The Law of Conservation of Videos.

Ok - let me start with an example. Suppose that 20 minutes of video are submitted every minute. If there was only one reviewer (with no movie speed ups) it would take the reviewer 20 minutes to review that video. So, what would happen for the next 20 minutes? You would need 20 more reviewers, where each one would start to review a movie and be unavailable for at least 20 minutes. In terms of my variables, this would be:

Note that the units work out fine since both s and n really don't have any units. Now, what if I want to include the efficiency? The greater the percent of time spent on administration stuff, the more people you would need. Then:

Units are still ok since efficiency also is unitless. What about the movie speed? The greater the movie speed for reviewing movies, the fewer reviewers google would need.

Units are still ok. To get the cost, I need n. Note that n is not how many people they need to hire, but how many people they need working (at any given time - assuming the video submission rate is constant).

So, how much would this cost a year? If the payrate (P) is in dollars per hour, then the yearly cost would be:

Now for the estimates

• P = $15/hr. I know this is much greater than minimum wage, but I am assuming there are other benefits costs and stuff.
• s = 20 min/min. Seems this is what they said on Buzz Out Loud. Of course, you could probably find a better value for this.
• e = 1.05. Total guess here. So 5% of the reviewing time is wasted. But maybe this should be even lower. What are the reviewers going to waste their time on? Watching youtube? I guess they could still play solitaire.
• v = 1.5. I picked 1.5 times for the playback speed because this is what the ipod does for podcasts if you want to listen faster. Works ok.

With these values, I get a yearly cost to google of 1.8 million dollars.

Update

Ok, I guess my guess of 20 minutes of video every minute was pretty wild. According to Youtube's fact sheet, they claim that 20 HOURS of video are uploaded each minute. This would change my estimate to 108 million dollars each year.

Thanks to the readers that pointed out my poor guess.