[TeMPOraL]

The size of the audio track is probably around 2% of the size of the whole video. I don't think they'll bother :).

[gremy0]

2% of a bazillions of dollars is still like nearly a bazillion dollars.

[TeMPOraL]

They'd have to either strip audio out of the video stream on the fly, which will probably force them to use less "dumb" CDNs and incur a processing time cost (which, like most today's on-line businesses, they happily offload to their users now), or they'd have to keep two copies of the same video on their servers, which would make it cost 2x "a bazillions of dollars".

[gremy0]

You are very probably right the simple solution makes sense. It is an interesting optimization to be able to make though.