[alwillis]

Is that a political or technical decision?

One obvious technical issue is that, as far as we know, there's no VP8 decoding hardware in any of Apple's products; implementing VP8 decoding in software might be more of a power drain than Apple wanted.

[clouddrover]

> there's no VP8 decoding hardware in any of Apple's products

But what I found interesting in the WWDC session you linked to was that a lot of Apple products don't have hardware HEVC decode and\or hardware HEVC encode support. Apple has implemented software HEVC decoding and encoding in a lot of places. From that perspective, adding support for VP8 and VP9 wouldn't be much different.