Despite the fact that Firefox can play content up to 4K natively on YouTube, only Internet Explorer and Microsoft Edge on Windows, and Safari on Mac, support 1080p HTML5 player streams while Chrome, Firefox and Opera only streams up to 720p in quality.

I don't know the technical reason why Netflix doesn't allow 1080p streams and up natively but have you tried pressing CTRL + SHIFT + S while watching Netflix to change the bitrate (resolution)? If it has an option above 3000, then its available in 1080p and up depending on how high it goes.

I did mange to find a quote on ghacks regarding this but its not verified.

"HTML5 hasn't had its DRM standardised yet and until it is the browsers looking to abide by standards won't get 1080p. It's only IE 11 on Win8 [and now Win10 and also Edge - ed.] which takes MS standard approach of going their own way and not following standards which has a DRM that's been fully accepted by the Movie/TV industry

DRM is to blame.

Thank you Moses, I didn't understand what you mean by "can play content up to 4k natively on Youtube [but does not support 1080p streaming] in HTML5]". These two statements seem to contradict each other. Or do you mean it can stream 4k in flash but not with HTML5? If I play a youtube video in Firefox and set it to 4k will it play it in 4k then? If so, then where does the 720p limit come into play?

¹I didn't understand what you mean by "can play content up to 4k natively on Youtube [but does not support 1080p streaming] in HTML5]".

²These two statements seem to contradict each other. Or do you mean it can stream 4k in flash but not with HTML5? If I play a youtube video in Firefox and set it to 4k will it play it in 4k then?

³If so, then where does the 720p limit come into play?

¹Firefox can play content on YouTube using HTML5 up to 4K natively if the video has the option to and if you have a 4K display. Looking at 4K content on a 1080p screen seems pointless but if you like doing that, go ahead. However, on Netflix (and only Netflix that I've noticed), Firefox can only play up to 720p using the HTML5 player even when manually trying to change the bitrate via Ctrl + Alt + Shift + S (not Ctrl + Alt + S as mentioned above).

² I don't use Flash so I don't know if it streams in 4k or not on YouTube but it should. If you play a video in YouTube on Firefox and set it to 4k using the HTML5 player, it'll play as expected. ³The 720p limit comes into play only on Netflix from what I've experienced. Below is me clarifying my first paragraph on the first comment.

Should've been

Despite the fact that Firefox can play content up to 4K natively on YouTube, I've noticed that Netflix's HTML5 player limits its stream to 720p on Firefox and Chrome while Internet Explorer and Microsoft Edge can go up to 1080p and 4K if the title supports it.

I'm unsure why IE/MSE are unaffected by the 720p limitation but I'm sure someone else on the forum has an answer.

Thanks! So Firefox does support 4k and Netflix seems to be limited for some reason. This is a bit technical, but please bear with me. I'm trying to decide whether to buy a 7th generation processor (Intel Kaby Lake) The main advantage of Kaby Lake over it's predecessor is the new 4k hardware decoding (HEVC and BP-9), see article below. 4k is very important to me, but I will not migrate to Windows 10. I will stick with Windows 7, so my question is can (or will) Firefox be able to take advantage of the hardware 4k decoding capabilites offered by Kaby Lake and other Gen7 chips while running under Windows 7?

http://www.theinquirer.net/inquirer/news/2469019/intels-7th-gen-core-kaby-lake-chip-takes-aim-at-4k-uhd-and-vr-content

I did some digging and I'll post what I found below.

On the subject of Netflix not supporting 1080p and up on Firefox, I found these on a PCmag article.

Netflix uses the 10-bit HEVC video-compression standard, also known as H.265, and Hollywood insists on DRM wrapped around its content.

In order for Netflix 4K streams to work you're going to need Intel's latest 7th-gen Kaby Lake processor. You'll also need to watch using Microsoft's Edge browser.

The Microsoft Edge requirement is due to the use of digital rights management (DRM) to protect the streams from being recorded and copied. Edge fully supports this protection.

Yet, Netflix streams in 1080p and 4k still get leaked...

On the subject of being able to utilize 4k hardware decoding on Kaby Lake and other 7th-gen chips, from what I've read, it seems like there's a Windows 10 requirement imposed by Microsoft.

^{https://blogs.windows.com/windowsexperience/2016/01/15/windows-10-embracing-silicon-innovation/#AzPiicZ8KVFYAvQz.97}

Thanks very much!