Given the crazy number of codecs out there, it's highly likely they're still using the FFMPEG libraries for transcoding (as is everyone else: Vimeo, FB, etc.). At MySpace we used DirectShow since the backend was Microsoft-based. Everything is transcoded for QoS (quality of service and also security reasons).
Google didn't create VP9, it's the latest iteration of the On2 codec, which Google purchased. VP10 is already out (code); doesn't appear to be in products yet. VP9 is the 'open source' alternate for H.265. However once you understand the patent system and corporations, it's all a game based on who has the most money to bend the markets to their will resulting in strange product support and crippling (I wrote two granted patents; perhaps all those years in the tech and entertainment businesses is why I'm now a philosopher
).
I think the reason 1080p got a recent quality boost (in Chrome and Windows Edge) was the additional transcode to VP9 instead of only H.264, where VP9 effectively provides about a 2x boost in bitrate-quality in supported browsers (i.e. not Safari lol: that's why no 4K in Safari and now likely why 1080p looks worse vs. VP9 browsers. Why doesn't Apple support VP9? See above comment about patents and corporations (does Apple support H.265?
))).
Google didn't create VP9, it's the latest iteration of the On2 codec, which Google purchased. VP10 is already out (code); doesn't appear to be in products yet. VP9 is the 'open source' alternate for H.265. However once you understand the patent system and corporations, it's all a game based on who has the most money to bend the markets to their will resulting in strange product support and crippling (I wrote two granted patents; perhaps all those years in the tech and entertainment businesses is why I'm now a philosopher
I think the reason 1080p got a recent quality boost (in Chrome and Windows Edge) was the additional transcode to VP9 instead of only H.264, where VP9 effectively provides about a 2x boost in bitrate-quality in supported browsers (i.e. not Safari lol: that's why no 4K in Safari and now likely why 1080p looks worse vs. VP9 browsers. Why doesn't Apple support VP9? See above comment about patents and corporations (does Apple support H.265?