Your comment: H264 is supported by pretty much all browsers. VP9 and H265 / HEVC have less support.
My response: That is a issue of browsers for not keeping up.
No, it's because HEVC has complicated licensing and browsers may have to pay fees to decode HEVC encoded videos. HEVC is supported in Edge because Windows itself has a plugin.
For a long time, Firefox did not support H264 because of licensing costs and complications. Cisco basically released a free decoder and they pay some yearly licensing fee and that's how everybody gets H264 decoding in Firefox and potentially other browsers.
Oh, VP9 also requires processors with SSE2 to decode content or some other newer cpu instructions, while I could still watch h264 encoded videos on Youtube on my IBM T40 laptop with a single core Intel Centrino 1.5 ghz processor. That's not possible with VP9, even if the video would be low bitrate and low resolution.
Your comment: H264 have very wide support for HARDWARE DECODING in video cards (very good for laptops, saving your battery).
My response: Do you expect YouTube to support H.264 forever?
H264 is one of the codecs in the HTML5 video specification, so it should be supported for a long time. See
https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats Browsers still support MP3 and that one was around the MPEG-2 times , and now all the patents for MP3 expired so it's free to use.
H264 is also used in Blurays and HEVC is used in 4K blurays ... Apple is also pushing for HEVC (H265) with their HEIF image format (basically intraframe HEVC) to replace JPG and PNG images so HEVC support will be inside the phone processors and supported for a long time. See
https://en.wikipedia.org/wiki/High_Efficiency_Image_File_FormatOther than Youtube saving money on bandwidth and licensing by going with VP9, there's not much reason to use VP9
Your comment: I'm not up to date with VP9 encoders but as far as I know, VP9 encoders are much slower than h264 (x264) or even HEVC encoders (x265).
My response: VP9 is faster to encode on CPU than H.265, Dave is doing low bitrate for his downloads aka GPU's would ruin the quality of the video.
I guess it depends how you tweak the encoder. At least both x264 and x265 have presets from ultrafast to veryslow and placebo, while last time I checked VP9 encoders have fewer configuration options and they're more inflexible.
Your comment: All the latest video cards (Pascal and Polaris and Vega) have HARDWARE ENCODING support for H264 and HEVC. H264 hardware encoding is supported by even older video cards.
My response: As I said Dave uses low bitrates, as such hardware rendering would ruin their quality.
It's debatable. In fact, for videos like the one Dave makes (talking heads and closeup of circuit boards so mostly static stuff) hardware encoding would produce quite decent results.
Your comment: Anyway, tldr is H264 for higher compatibility , HEVC would work great for file downloads, VP9 pretty much only for html5 video playback in browser in Chrome and Firefox maybe.
My response: H.264 is old and outdated. H.265 is too expensive
In the end, bandwidth is cheap. I'd rather upload 1.1 GB h264 with same quality as 1 GB VP9 encoded content but encode the video ten times faster using x264.
Unless you really have to achieve the best quality possible within a bitrate (let's say you want 300 kbps vbr and max 1mbps peak over a 5s time period or something like that) there's probably little reason to work several times for so little benefit.
Not to mention that if you don't care about hardware decoding, you could also encode with h264 10bit mode and that will bring the quality even closer to vp9