H265 aka HEVC is the successor of the H264 video format.
HEVC is said to double the data compression ratio compared to H.264/MPEG-4 AVC at the same level of video quality. It can alternatively be used to provide substantially improved video quality at the same bit rate. It can support 8K UHD and resolutions up to 8192×4320.
What about to support this in Microsoft Edge and IE?
@PaintNinja, HEVC is only natively supported in Windows 10 if you have hardware support for it, such as with one of the fairly narrow range of new video cards that supports it (not speaking of 3rd-party software like VLC). Clearly, you have the hardware.
During the Windows 10 beta, HEVC was supported on any system, but no more.
I have tested and can confirm that h.265 (HEVC) is already supported in Microsoft Edge in supported containers such as the .mp4 container. Tested using videos from https://x265.com/hevc-video-files/ and opening the saved videos in Edge.
I believe HEVC is already supported in Microsoft Edge and IE11 on Windows 10, as well as natively on the OS.
Currently VP9 seems to have a better and faster encoder, and VP9 is supported in Edge already.
Given that, and the fact that HEVC has even worse licensing terms than H.264 did, it may be fine to skip it.