Probably not for serving user requests for content.

But, if Youtube archived the original upload on tape before transcoding to a different format, then it would be useful. The tapes would really only be "read," in a batch manner, when they want to re-transcode to a newer codec.

Likewise, tape would be a great way to store the digital equivalent of the "negatives" once a movie, TV show, or music album is complete. No one needs instant, on-demand, random access to every shot, every take, and every camera angle. It can be pulled off the tape in 10 years when producing the Nth remaster for the new super-duper bluray version.

Tape provides linear access. The limits of AWS Glacier are probably a good place to start back of napkin latency calculations. https://aws.amazon.com/glacier/

According to https://en.wikipedia.org/wiki/Linear_Tape-Open#Positioning_t... , in the region of 50 seconds, which isn't really good enough.

I'm sure there's long-tail data on YouTube for which terabytes of files that could be backed up to tape are accessed far more slowly than every 50 seconds. I agree that this would not be a great user experience, but there's certainly a place for it, especially if the cost/terabyte is compelling.

The other problem is that Hard Drives are cheap as hell and tapes, especially ones loaded into automatic robots, are really not that cheap.

It's the perennial disappointment with tape drives that the media has "enterprise" pricing, making it barely better per TB than cheap consumer spinning hard drives.